Unique physicochemical properties of two-dimensional light absorbers facilitating photocatalysis.

The emergence of two-dimensional (2D) materials with a large lateral size and extremely small thickness has significantly changed the development of many research areas by producing a variety of unusual physicochemical properties. Semiconductor photocatalysis is intrinsically controlled by multiple light-matter, light absorber-cocatalyst and molecular/ionic-matter interactions that can be highly dependent on the geometric features of the light absorber. In this review, we focus on the unique structures and unusual physicochemical properties of 2D semiconducting light absorbers and their roles in facilitating photocatalysis. In particular, we highlight their structure-property relationships considering the unique electronic structure, optical absorption, spatial separation of charge carriers, structural advantages as a host of active guests, and the strain-modulated band structures of the 2D light absorbers. The representative development of a number of 2D light absorbers with structural/compositional features such as nonporous and porous structures, heteroatom/defect modification and manufactured hybrid structures for photocatalysis are discussed in detail. We conclude with a discussion of some key challenges and future directions for the development of 2D photocatalysts for efficient solar energy conversion.

[1]  Kevin Barraclough,et al.  I and i , 2001, BMJ : British Medical Journal.

[2]  M. Matsuka,et al.  Preparation of tantalum-based oxynitride nanosheets by exfoliation of a layered oxynitride, CsCa2Ta3O(10-x)N(y), and their photocatalytic activity. , 2012, Journal of the American Chemical Society.

[3]  Zhenyi Zhang,et al.  Hierarchical Sheet-on-Sheet ZnIn2S4/g-C3N4 Heterostructure with Highly Efficient Photocatalytic H2 production Based on Photoinduced Interfacial Charge Transfer , 2016, Scientific Reports.

[4]  L. Qu,et al.  One-step preparation of iodine-doped graphitic carbon nitride nanosheets as efficient photocatalysts for visible light water splitting , 2015 .

[5]  M. Pourfath,et al.  Modulation of electronic and mechanical properties of phosphorene through strain , 2014, 1407.7706.

[6]  Qiang Fu,et al.  Catalysis with two-dimensional materials and their heterostructures. , 2016, Nature nanotechnology.

[7]  T. Sasaki,et al.  First-Principles Study of Two-Dimensional Titanium Dioxides , 2003 .

[8]  Xiaoping Dong,et al.  Recent development in exfoliated two-dimensional g-C3N4 nanosheets for photocatalytic applications , 2015 .

[9]  Can Li,et al.  Roles of cocatalysts in photocatalysis and photoelectrocatalysis. , 2013, Accounts of chemical research.

[10]  Jiaguo Yu,et al.  Metal‐Free 2D/2D Phosphorene/g‐C3N4 Van der Waals Heterojunction for Highly Enhanced Visible‐Light Photocatalytic H2 Production , 2018, Advanced materials.

[11]  Pingquan Wang,et al.  Bismuth-rich Bi4O5X2 (X = Br, and I) nanosheets with dominant {1 0 1} facets exposure for photocatalytic H2 evolution , 2016 .

[12]  V. Colvin,et al.  Shape matters , 2003, Nature materials.

[13]  Yi Luo,et al.  Molecular co-catalyst accelerating hole transfer for enhanced photocatalytic H2 evolution , 2015, Nature Communications.

[14]  Lingyan Zhu,et al.  Enhanced photocatalytic performance of boron doped Bi₂WO₆ nanosheets under simulated solar light irradiation. , 2013, Journal of hazardous materials.

[15]  Minqi Sheng,et al.  Hydrothermal route to metastable phase FeVO4 ultrathin nanosheets with exposed {010} facets: synthesis, photocatalysis and gas-sensing , 2014 .

[16]  S. Seal,et al.  Recent development in 2D materials beyond graphene , 2015 .

[17]  Lianzhou Wang,et al.  Recent advances in 2D materials for photocatalysis. , 2016, Nanoscale.

[18]  E. Kan,et al.  Visible-Light-Absorption in Graphitic C3N4 Bilayer: Enhanced by Interlayer Coupling , 2012 .

[19]  G. Qian,et al.  A review on fabricating heterostructures from layered double hydroxides for enhanced photocatalytic activities , 2018 .

[20]  Jun Jiang,et al.  Implementing Metal‐to‐Ligand Charge Transfer in Organic Semiconductor for Improved Visible‐Near‐Infrared Photocatalysis , 2016, Advanced materials.

[21]  Zhigang Chen,et al.  Enhanced photocatalytic hydrogen evolution by prolonging the lifetime of carriers in ZnO/CdS heterostructures. , 2009, Chemical communications.

[22]  Yi Xie,et al.  Free-floating ultrathin tin monoxide sheets for solar-driven photoelectrochemical water splitting , 2014 .

[23]  P. Ajayan,et al.  Exfoliated Graphitic Carbon Nitride Nanosheets as Efficient Catalysts for Hydrogen Evolution Under Visible Light , 2013, Advanced materials.

[24]  Y. Xiong,et al.  Van der Waals Heterostructures Comprised of Ultrathin Polymer Nanosheets for Efficient Z-Scheme Overall Water Splitting. , 2018, Angewandte Chemie.

[25]  Chong Xiao,et al.  Vacancy associates promoting solar-driven photocatalytic activity of ultrathin bismuth oxychloride nanosheets. , 2013, Journal of the American Chemical Society.

[26]  Shiying Zhang,et al.  Insights into the role of Cu in promoting photocatalytic hydrogen production over ultrathin HNb3O8 nanosheets , 2016 .

[27]  Ze Zhang,et al.  Mesopores induced zero thermal expansion in single-crystal ferroelectrics , 2018, Nature Communications.

[28]  R. Dingle,et al.  Confined carrier quantum states in ultrathin semiconductor heterostructures , 1975 .

[29]  Bin Zhang,et al.  Synthesis of ultrathin CdS nanosheets as efficient visible-light-driven water splitting photocatalysts for hydrogen evolution. , 2013, Chemical communications.

[30]  Tongguang Xu,et al.  Monomolecular‐Layer Ba5Ta4O15 Nanosheets: Synthesis and Investigation of Photocatalytic Properties , 2006 .

[31]  Fang Song,et al.  Exfoliation of layered double hydroxides for enhanced oxygen evolution catalysis , 2014, Nature Communications.

[32]  Markus Antonietti,et al.  Carbon-doped BN nanosheets for metal-free photoredox catalysis , 2015, Nature Communications.

[33]  Z. Tang,et al.  Ultrathin two-dimensional layered metal hydroxides: an emerging platform for advanced catalysis, energy conversion and storage. , 2016, Chemical Society reviews.

[34]  X. Jiao,et al.  Monoclinic structured BiVO4 nanosheets: hydrothermal preparation, formation mechanism, and coloristic and photocatalytic properties. , 2006, The journal of physical chemistry. B.

[35]  Zhigang Chen,et al.  Construction of a 2D Graphene-Like MoS2/C3N4 Heterojunction with Enhanced Visible-Light Photocatalytic Activity and Photoelectrochemical Activity. , 2016, Chemistry.

[36]  Hui‐Ming Cheng,et al.  Design and construction of a film of mesoporous single-crystal rutile TiO2 rod arrays for photoelectrochemical water oxidation , 2015 .

[37]  T. Sasaki,et al.  Electronic Band Structure of Exfoliated Titanium- and/or Niobium-Based Oxide Nanosheets Probed by Electrochemical and Photoelectrochemical Measurements , 2012 .

[38]  Hui‐Ming Cheng,et al.  Selective Breaking of Hydrogen Bonds of Layered Carbon Nitride for Visible Light Photocatalysis , 2016, Advanced materials.

[39]  S. Ida,et al.  Photodeposition of Metal and Metal Oxide at the TiOx Nanosheet to Observe the Photocatalytic Active Site , 2008 .

[40]  K. Domen,et al.  A complex perovskite-type oxynitride: the first photocatalyst for water splitting operable at up to 600 nm. , 2015, Angewandte Chemie.

[41]  Chenghua Sun,et al.  Nitrogen-doped titania nanosheets towards visible light response. , 2009, Chemical communications.

[42]  T. Ishihara,et al.  Photocatalytic reaction centers in two-dimensional titanium oxide crystals. , 2015, Journal of the American Chemical Society.

[43]  M. Gao,et al.  High-performance photodetectors and enhanced photocatalysts of two-dimensional TiO2 nanosheets under UV light excitation. , 2016, Nanoscale.

[44]  Yadong Li,et al.  Ultrathin rhodium nanosheets , 2014, Nature Communications.

[45]  Siang-Piao Chai,et al.  Graphitic Carbon Nitride (g-C3N4)-Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer To Achieving Sustainability? , 2016, Chemical reviews.

[46]  SUPARNA DUTTASINHA,et al.  Van der Waals heterostructures , 2013, Nature.

[47]  Madan Dubey,et al.  Two-dimensional material nanophotonics , 2014, 1410.3882.

[48]  Hui‐Ming Cheng,et al.  Selective deposition of redox co-catalyst(s) to improve the photocatalytic activity of single-domain ferroelectric PbTiO₃ nanoplates. , 2014, Chemical communications.

[49]  Renzhi Ma,et al.  Nanosheets of Oxides and Hydroxides: Ultimate 2D Charge‐Bearing Functional Crystallites , 2010, Advanced materials.

[50]  Yanfang Liu,et al.  Defect-related photoluminescence and photocatalytic properties of porous ZnO nanosheets , 2014 .

[51]  Lizhi Zhang,et al.  Solar Water Splitting and Nitrogen Fixation with Layered Bismuth Oxyhalides. , 2017, Accounts of chemical research.

[52]  B. Dubertret,et al.  Colloidal nanoplatelets with two-dimensional electronic structure. , 2011, Nature materials.

[53]  Min Gyu Kim,et al.  A Crucial Role of Rh Substituent Ion in Photoinduced Internal Electron Transfer and Enhanced Photocatalytic Activity of CdS-Ti(5.2-x)/6 Rhx /2 O2 Nanohybrids. , 2015, Small.

[54]  Lizhi Zhang,et al.  Superior visible light hydrogen evolution of Janus bilayer junctions via atomic-level charge flow steering , 2016, Nature Communications.

[55]  Tomoki Akita,et al.  All-solid-state Z-scheme in CdS–Au–TiO2 three-component nanojunction system , 2006, Nature materials.

[56]  Jian Pan,et al.  Titanium dioxide crystals with tailored facets. , 2014, Chemical reviews.

[57]  C. Ziegler,et al.  Crystalline carbon nitride nanosheets for improved visible-light hydrogen evolution. , 2014, Journal of the American Chemical Society.

[58]  Xiaobo Chen,et al.  Increasing Solar Absorption for Photocatalysis with Black Hydrogenated Titanium Dioxide Nanocrystals , 2011, Science.

[59]  Y. Horiuchi,et al.  Understanding TiO2 photocatalysis: mechanisms and materials. , 2014, Chemical reviews.

[60]  N. Wu,et al.  Visible light photocatalytic activity of nitrogen-doped La2Ti2O7 nanosheets originating from band gap narrowing , 2012, Nano Research.

[61]  Aijun Du,et al.  Single Atom (Pd/Pt) Supported on Graphitic Carbon Nitride as an Efficient Photocatalyst for Visible-Light Reduction of Carbon Dioxide. , 2016, Journal of the American Chemical Society.

[62]  Gang Chen,et al.  Urea-assisted synthesis of ultra-thin hexagonal tungsten trioxide photocatalyst sheets , 2015, Journal of Materials Science.

[63]  Erwin M. Sabio,et al.  Single-Crystal Tungsten Oxide Nanosheets: Photochemical Water Oxidation in the Quantum Confinement Regime , 2012 .

[64]  Yi Luo,et al.  Combining photocatalytic hydrogen generation and capsule storage in graphene based sandwich structures , 2017, Nature Communications.

[65]  P. Ajayan,et al.  High Efficiency Photocatalytic Water Splitting Using 2D α‐Fe2O3/g‐C3N4 Z‐Scheme Catalysts , 2017 .

[66]  B. Pan,et al.  Oxygen vacancies confined in ultrathin indium oxide porous sheets for promoted visible-light water splitting. , 2014, Journal of the American Chemical Society.

[67]  J. Yates,et al.  Photocatalysis on TiO2 Surfaces: Principles, Mechanisms, and Selected Results , 1995 .

[68]  Thomas F. Jaramillo,et al.  Accelerating materials development for photoelectrochemical hydrogen production: Standards for methods, definitions, and reporting protocols , 2010 .

[69]  Kulamani Parida,et al.  A review on the recent progress, challenges and perspective of layered double hydroxides as promising photocatalysts , 2016 .

[70]  Yi Xie,et al.  Enhanced Photoexcited Carrier Separation in Oxygen-Doped ZnIn2 S4 Nanosheets for Hydrogen Evolution. , 2016, Angewandte Chemie.

[71]  Lianzhou Wang,et al.  An n-type to p-type switchable photoelectrode assembled from alternating exfoliated titania nanosheets and polyaniline layers. , 2013, Angewandte Chemie.

[72]  Zhiliang Wang,et al.  Enhancing charge separation on high symmetry SrTiO3 exposed with anisotropic facets for photocatalytic water splitting , 2016 .

[73]  Hua-ming Li,et al.  Freestanding atomically-thin two-dimensional materials beyond graphene meeting photocatalysis: Opportunities and challenges , 2017 .

[74]  Xiaobin Fan,et al.  Roles of Two-Dimensional Transition Metal Dichalcogenides as Cocatalysts in Photocatalytic Hydrogen Evolution and Environmental Remediation , 2017 .

[75]  Sean C. Smith,et al.  Band-to-Band Visible-Light Photon Excitation and Photoactivity Induced by Homogeneous Nitrogen Doping in Layered Titanates , 2009 .

[76]  T. Mallouk,et al.  Flat-Band Potentials of Molecularly Thin Metal Oxide Nanosheets. , 2016, ACS applied materials & interfaces.

[77]  B. Su,et al.  2D ZnO mesoporous single-crystal nanosheets with exposed {0001} polar facets for the depollution of cationic dye molecules by highly selective adsorption and photocatalytic decomposition , 2016 .

[78]  Can Li,et al.  Spatial separation of photogenerated electrons and holes among {010} and {110} crystal facets of BiVO4 , 2013, Nature Communications.

[79]  Hyungjun Kim,et al.  A Conductive Hybridization Matrix of RuO2 Two-Dimensional Nanosheets: A Hybrid-Type Photocatalyst. , 2016, Angewandte Chemie.

[80]  T. Majima,et al.  Z-Scheme Photocatalytic Water Splitting on a 2D Heterostructure of Black Phosphorus/Bismuth Vanadate Using Visible Light. , 2018, Angewandte Chemie.

[81]  Z. Yin,et al.  Hierarchical hollow spheres composed of ultrathin Fe2O3 nanosheets for lithium storage and photocatalytic water oxidation , 2013 .

[82]  Hao Wang,et al.  Hydrothermal synthesis and photocatalytic properties of layered La2Ti2O7 nanosheets , 2006 .

[83]  Hui‐Ming Cheng,et al.  Graphene‐Like Carbon Nitride Nanosheets for Improved Photocatalytic Activities , 2012 .

[84]  Yi Xie,et al.  Spatial location engineering of oxygen vacancies for optimized photocatalytic H2 evolution activity. , 2014, Small.

[85]  Maor F. Baruch,et al.  Light-Driven Heterogeneous Reduction of Carbon Dioxide: Photocatalysts and Photoelectrodes. , 2015, Chemical reviews.

[86]  Yi Xie,et al.  Single Unit Cell Bismuth Tungstate Layers Realizing Robust Solar CO2 Reduction to Methanol. , 2015, Angewandte Chemie.

[87]  Lianzhou Wang,et al.  Titanium oxide nanosheets: graphene analogues with versatile functionalities. , 2014, Chemical reviews.

[88]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[89]  Bin Luo,et al.  Single‐Crystalline Nanomesh Tantalum Nitride Photocatalyst with Improved Hydrogen‐Evolving Performance , 2018 .

[90]  Pingquan Wang,et al.  g-C3N4/Bi4O5I2 heterojunction with I3−/I− redox mediator for enhanced photocatalytic CO2 conversion , 2016 .

[91]  Zhenyi Zhang,et al.  Ultrathin hexagonal SnS2 nanosheets coupled with g-C3N4 nanosheets as 2D/2D heterojunction photocatalysts toward high photocatalytic activity , 2015 .

[92]  Jinlin Li,et al.  Synthesis and characterization of visible light responsive Bi3NbO7 porous nanosheets photocatalyst , 2016 .

[93]  C. Zhang,et al.  Design of BN porous sheets with richly exposed (002) plane edges and their application as TiO2 visible light sensitizer , 2015 .

[94]  I. Sharp,et al.  Scalable water splitting on particulate photocatalyst sheets with a solar-to-hydrogen energy conversion efficiency exceeding 1. , 2016, Nature materials.

[95]  X. Lou,et al.  Defect‐Rich MoS2 Ultrathin Nanosheets with Additional Active Edge Sites for Enhanced Electrocatalytic Hydrogen Evolution , 2013, Advanced materials.

[96]  Tae Woo Kim,et al.  Mesoporous layer-by-layer ordered nanohybrids of layered double hydroxide and layered metal oxide: highly active visible light photocatalysts with improved chemical stability. , 2011, Journal of the American Chemical Society.

[97]  Yi Xie,et al.  Freestanding tin disulfide single-layers realizing efficient visible-light water splitting. , 2012, Angewandte Chemie.

[98]  Fan Zuo,et al.  Branched WO3 Nanosheet Array with Layered C3N4 Heterojunctions and CoOx Nanoparticles as a Flexible Photoanode for Efficient Photoelectrochemical Water Oxidation , 2014, Advanced materials.

[99]  P. Ajayan,et al.  Room-temperature ferroelectricity in CuInP2S6 ultrathin flakes , 2016, Nature Communications.

[100]  Sean C. Smith,et al.  Bandgap narrowing of titanium oxide nanosheets: homogeneous doping of molecular iodine for improved photoreactivity , 2011 .

[101]  Hui‐Ming Cheng,et al.  Enhanced Photocatalytic H2 Production in Core–Shell Engineered Rutile TiO2 , 2016, Advanced materials.

[102]  Xinchen Wang,et al.  Activation of n → π* Transitions in Two-Dimensional Conjugated Polymers for Visible Light Photocatalysis , 2014 .

[103]  A S Rodin,et al.  Strain-induced gap modification in black phosphorus. , 2014, Physical review letters.

[104]  Xiaobo Chen,et al.  Titanium dioxide-based nanomaterials for photocatalytic fuel generations. , 2014, Chemical reviews.

[105]  Yongsheng Zhu,et al.  Layered nanojunctions for hydrogen-evolution catalysis. , 2013, Angewandte Chemie.

[106]  Hao Liu,et al.  Single-layer Group-IVB nitride halides as promising photocatalysts , 2014 .

[107]  Qinghua Xu,et al.  Self-surface charge exfoliation and electrostatically coordinated 2D hetero-layered hybrids , 2017, Nature Communications.

[108]  T. Ishihara,et al.  Black-colored nitrogen-doped calcium niobium oxide nanosheets and their photocatalytic properties under visible light irradiation , 2013 .

[109]  Front , 2020, 2020 Fourth World Conference on Smart Trends in Systems, Security and Sustainability (WorldS4).

[110]  Xiaodong Chen,et al.  Heterogeneous visible light photocatalysis for selective organic transformations. , 2014, Chemical Society reviews.

[111]  M. Zhukovskyi,et al.  Efficient Photocatalytic Hydrogen Generation from Ni Nanoparticle Decorated CdS Nanosheets , 2015 .

[112]  R. Asahi,et al.  Nitrogen-doped titanium dioxide as visible-light-sensitive photocatalyst: designs, developments, and prospects. , 2014, Chemical reviews.

[113]  Hironori Arakawa,et al.  Direct splitting of water under visible light irradiation with an oxide semiconductor photocatalyst , 2001, Nature.

[114]  Shuquan Huang,et al.  Synthesis and photocatalytic activity of g-C3N4/BiOI/BiOBr ternary composites , 2016 .

[115]  R. Ahuja,et al.  Design of high-efficiency visible-light photocatalysts for water splitting: MoS2/AlN(GaN) heterostructures , 2014 .

[116]  Yi Xie,et al.  Atomically-thin two-dimensional sheets for understanding active sites in catalysis. , 2015, Chemical Society reviews.

[117]  Yi Xie,et al.  Highly Efficient and Exceptionally Durable CO2 Photoreduction to Methanol over Freestanding Defective Single-Unit-Cell Bismuth Vanadate Layers. , 2017, Journal of the American Chemical Society.

[118]  Xiaofeng Qian,et al.  Strain-engineered artificial atom as a broad-spectrum solar energy funnel , 2012, Nature Photonics.

[119]  Kazunori Takada,et al.  Electronic band structure of titania semiconductor nanosheets revealed by electrochemical and photoelectrochemical studies. , 2004, Journal of the American Chemical Society.

[120]  Xinchen Wang,et al.  Two-dimensional covalent carbon nitride nanosheets: synthesis, functionalization, and applications , 2015 .

[121]  J. Shan,et al.  Atomically thin MoS₂: a new direct-gap semiconductor. , 2010, Physical review letters.

[122]  Hui‐Ming Cheng,et al.  Enhanced photocatalytic hydrogen generation of mesoporous rutile TiO2 single crystal with wholly exposed {111} facets , 2015 .

[123]  Hui-Ming Cheng,et al.  Unique electronic structure induced high photoreactivity of sulfur-doped graphitic C3N4. , 2010, Journal of the American Chemical Society.

[124]  Xinxin Zhang,et al.  Ultra-thin C3N4 nanosheets for rapid charge transfer in the core–shell heterojunction of α-sulfur@C3N4 for superior metal-free photocatalysis under visible light , 2015 .

[125]  Yihe Zhang,et al.  g-C3N4/Bi4O5I2 2D–2D heterojunctional nanosheets with enhanced visible-light photocatalytic activity , 2016 .

[126]  Hongwei Lu,et al.  Constructing Anatase TiO2 Nanosheets with Exposed (001) Facets/Layered MoS2 Two-Dimensional Nanojunctions for Enhanced Solar Hydrogen Generation , 2016 .

[127]  Jiaguo Yu,et al.  Graphene-Based Photocatalysts for Hydrogen Generation. , 2013, The journal of physical chemistry letters.

[128]  Hui‐Ming Cheng,et al.  An Amorphous Carbon Nitride Photocatalyst with Greatly Extended Visible‐Light‐Responsive Range for Photocatalytic Hydrogen Generation , 2015, Advanced materials.

[129]  J. Xu,et al.  Chemical exfoliation of graphitic carbon nitride for efficient heterogeneous photocatalysis , 2013 .

[130]  R. Stephenson.  A and V , 1962, The British journal of ophthalmology.

[131]  Wei Guo,et al.  Surface Ti3+/ Ti4+ Redox Shuttle Enhancing Photocatalytic H2 Production in Ultrathin TiO2 Nanosheets/CdSe Quantum Dots , 2015 .

[132]  Yangen Zhou,et al.  Monolayered Bi2WO6 nanosheets mimicking heterojunction interface with open surfaces for photocatalysis , 2015, Nature Communications.

[133]  Junhong Chen,et al.  Constructing 2D Porous Graphitic C3N4 Nanosheets/Nitrogen‐Doped Graphene/Layered MoS2 Ternary Nanojunction with Enhanced Photoelectrochemical Activity , 2013, Advanced materials.

[134]  Artem R. Oganov,et al.  Synthesis of borophenes: Anisotropic, two-dimensional boron polymorphs , 2015, Science.

[135]  Thomas F. Jaramillo,et al.  Identification of Active Edge Sites for Electrochemical H2 Evolution from MoS2 Nanocatalysts , 2007, Science.

[136]  Jinlong Yang,et al.  Proposed photosynthesis method for producing hydrogen from dissociated water molecules using incident near-infrared light. , 2014, Physical review letters.

[137]  Zhenzhen Lin,et al.  Nanostructure engineering and doping of conjugated carbon nitride semiconductors for hydrogen photosynthesis. , 2013, Angewandte Chemie.

[138]  H. Bechtel,et al.  Quantum of optical absorption in two-dimensional semiconductors , 2013, Proceedings of the National Academy of Sciences of the United States of America.

[139]  Dermot O'Hare,et al.  Recent advances in the synthesis and application of layered double hydroxide (LDH) nanosheets. , 2012, Chemical reviews.

[140]  Hua-ming Li,et al.  Ultrathin 2D Photocatalysts: Electronic‐Structure Tailoring, Hybridization, and Applications , 2018, Advanced materials.

[141]  T. Ishihara,et al.  Synthesis and photocatalytic activity of rhodium-doped calcium niobate nanosheets for hydrogen production from a water/methanol system without cocatalyst loading. , 2011, Journal of the American Chemical Society.

[142]  Yongtao Lu,et al.  Exfoliated carbon nitride nanosheets decorated with NiS as an efficient noble-metal-free visible-light-driven photocatalyst for hydrogen evolution. , 2015, Physical chemistry chemical physics : PCCP.

[143]  Hee Jo Song,et al.  Enhanced Photocatalytic Activity of Ultrathin Ba5Nb4O15 Two-Dimensional Nanosheets. , 2015, ACS applied materials & interfaces.

[144]  Hiroshi Segawa,et al.  Small Photocarrier Effective Masses Featuring Ambipolar Transport in Methylammonium Lead Iodide Perovskite: A Density Functional Analysis. , 2013, The journal of physical chemistry letters.

[145]  J. Y. Kim,et al.  Calcium Niobate Semiconductor Nanosheets as Catalysts for Photochemical Hydrogen Evolution from Water , 2007 .

[146]  X. Lou,et al.  Two-dimensional nanosheets for photoelectrochemical water splitting: Possibilities and opportunities , 2013 .

[147]  Xuri Huang,et al.  Unique Electronic Structure in a Porous Ga-In Bimetallic Oxide Nano-Photocatalyst with Atomically Thin Pore Walls. , 2016, Angewandte Chemie.

[148]  Jin Zou,et al.  Anatase TiO2 single crystals with a large percentage of reactive facets , 2008, Nature.

[149]  W. Marsden.  I and J , 2012 .

[150]  O. Hod,et al.  Edge Chemistry Effects on the Structural, Electronic, and Electric Response Properties of Boron Nitride Quantum Dots , 2014, 1404.4264.

[151]  O. C. Compton,et al.  A Building Block Approach to Photochemical Water-Splitting Catalysts Based on Layered Niobate Nanosheets , 2008 .

[152]  T. Taniguchi,et al.  Massive Dirac Fermions and Hofstadter Butterfly in a van der Waals Heterostructure , 2013, Science.

[153]  M. Jaroniec,et al.  Earth-abundant cocatalysts for semiconductor-based photocatalytic water splitting. , 2014, Chemical Society reviews.

[154]  Dan Qu,et al.  Synthesis of Carbon Dots with Multiple Color Emission by Controlled Graphitization and Surface Functionalization , 2018, Advanced materials.

[155]  Chunhua Lu,et al.  Selectivity Enhancement in Heterogeneous Photocatalytic Transformations. , 2017, Chemical reviews.

[156]  Hongzheng Chen,et al.  Graphene-like two-dimensional materials. , 2013, Chemical reviews.

[157]  Mamoru Watanabe,et al.  Macromolecule-like Aspects for a Colloidal Suspension of an Exfoliated Titanate. Pairwise Association of Nanosheets and Dynamic Reassembling Process Initiated from It , 1996 .

[158]  Sean C. Smith,et al.  N‐Doped CsTaWO6 as a New Photocatalyst for Hydrogen Production from Water Splitting Under Solar Irradiation , 2011 .

[159]  Xinchen Wang,et al.  Graphitic Carbon Nitride Polymers toward Sustainable Photoredox Catalysis. , 2015, Angewandte Chemie.

[160]  P. G. Harper,et al.  Exciton spectra in thin crystals , 1968 .

[161]  Satishchandra Ogale,et al.  g-C3N4/NiAl-LDH 2D/2D Hybrid Heterojunction for High-Performance Photocatalytic Reduction of CO2 into Renewable Fuels. , 2018, ACS applied materials & interfaces.

[162]  R. Ahuja,et al.  Review of two-dimensional materials for photocatalytic water splitting from a theoretical perspective , 2017 .

[163]  Y. Mi,et al.  Ultrathin Lanthanum Tantalate Perovskite Nanosheets Modified by Nitrogen Doping for Efficient Photocatalytic Water Splitting. , 2017, ACS nano.

[164]  J. Chen,et al.  The dominant {001} facet-dependent enhanced visible-light photoactivity of ultrathin BiOBr nanosheets. , 2014, Physical chemistry chemical physics : PCCP.

[165]  B. Pan,et al.  Structural distortion in graphitic-C3N4 realizing an efficient photoreactivity. , 2015, Nanoscale.

[166]  Takuya Hayashi,et al.  Remarkably high apparent quantum yield of the overall photocatalytic H2O splitting achieved by utilizing Zn ion added Ga2O3 prepared using dilute CaCl2 solution. , 2015, Chemical communications.

[167]  Ling Wu,et al.  Efficient synthesis of monolayer carbon nitride 2D nanosheet with tunable concentration and enhanced visible-light photocatalytic activities , 2015 .

[168]  Ya-Fan Zhao,et al.  Planar hexagonal B36 as a potential basis for extended single-atom layer boron sheets , 2014, Nature Communications.

[169]  Porun Liu,et al.  Engineered Hematite Mesoporous Single Crystals Drive Drastic Enhancement in Solar Water Splitting. , 2016, Nano letters.

[170]  L. D. A. Siebbeles,et al.  Long-range orientation and atomic attachment of nanocrystals in 2D honeycomb superlattices , 2014, Science.

[171]  Jindui Hong,et al.  Porous carbon nitride nanosheets for enhanced photocatalytic activities. , 2014, Nanoscale.

[172]  Xi‐Wen Du,et al.  Porous P-doped graphitic carbon nitride nanosheets for synergistically enhanced visible-light photocatalytic H2 production , 2015 .

[173]  K. Domen,et al.  Particulate photocatalysts for overall water splitting , 2017 .

[174]  Jed I. Ziegler,et al.  Bandgap engineering of strained monolayer and bilayer MoS2. , 2013, Nano letters.

[175]  C. Tung,et al.  Facile synthesis of ultrathin SnNb2O6 nanosheets towards improved visible-light photocatalytic H2-production activity. , 2016, Chemical communications.

[176]  Kazuhiro Takanabe,et al.  Synthesis of a carbon nitride structure for visible-light catalysis by copolymerization. , 2010, Angewandte Chemie.

[177]  Hui‐Ming Cheng,et al.  Noninvasively Modifying Band Structures of Wide‐Bandgap Metal Oxides to Boost Photocatalytic Activity , 2018, Advanced materials.

[178]  Sharath Sriram,et al.  Elemental analogues of graphene: silicene, germanene, stanene, and phosphorene. , 2015, Small.

[179]  Single-layer MoS2 as an efficient photocatalyst , 2012, 1211.4052.

[180]  Henry J. Snaith,et al.  Mesoporous TiO2 single crystals delivering enhanced mobility and optoelectronic device performance , 2013, Nature.

[181]  T. Majima,et al.  Metal-Free Photocatalyst for H2 Evolution in Visible to Near-Infrared Region: Black Phosphorus/Graphitic Carbon Nitride. , 2017, Journal of the American Chemical Society.

[182]  Tae Woo Kim,et al.  A strong electronic coupling between graphene nanosheets and layered titanate nanoplates: a soft-chemical route to highly porous nanocomposites with improved photocatalytic activity. , 2012, Small.

[183]  Gerbrand Ceder,et al.  Identification and design principles of low hole effective mass p-type transparent conducting oxides , 2013, Nature Communications.

[184]  Bicai Pan,et al.  Enhanced photoresponsive ultrathin graphitic-phase C3N4 nanosheets for bioimaging. , 2013, Journal of the American Chemical Society.

[185]  Yi Xie,et al.  All‐Surface‐Atomic‐Metal Chalcogenide Sheets for High‐Efficiency Visible‐Light Photoelectrochemical Water Splitting , 2014 .

[186]  Suhye Park,et al.  A facile exfoliation-crystal growth route to multicomponent Ag₂CO₃/Ag-Ti₅NbO₁₄ nanohybrids with improved visible light photocatalytic activity. , 2014, Dalton transactions.

[187]  Jiaguo Yu,et al.  Two-dimensional layered composite photocatalysts. , 2014, Chemical communications.

[188]  G. Lu,et al.  Achieving maximum photo-oxidation reactivity of Cs(0.68)Ti(1.83)O(4-x)N(x) photocatalysts through valence band fine-tuning , 2011 .

[189]  T. Sasaki,et al.  Restacked Perovskite Nanosheets and Their Pt-Loaded Materials as Photocatalysts , 2002 .

[190]  David G. Evans,et al.  NiTi-Layered double hydroxides nanosheets as efficient photocatalysts for oxygen evolution from water using visible light , 2014 .

[191]  Frank E. Osterloh,et al.  CdSe-MoS2: A Quantum Size-Confined Photocatalyst for Hydrogen Evolution from Water under Visible Light , 2010 .

[192]  Wei Zhang,et al.  Carbon nitride nanosheets for photocatalytic hydrogen evolution: remarkably enhanced activity by dye sensitization , 2013 .

[193]  J. Yates,et al.  Band bending in semiconductors: chemical and physical consequences at surfaces and interfaces. , 2012, Chemical reviews.

[194]  Lianzhou Wang,et al.  Titania-based photocatalysts—crystal growth, doping and heterostructuring , 2010 .

[195]  K. Maeda,et al.  Perovskite oxide nanosheets with tunable band-edge potentials and high photocatalytic hydrogen-evolution activity. , 2014, Angewandte Chemie.

[196]  A. D. Yoffe,et al.  Low-dimensional systems: Quantum size effects and electronic properties of semiconductor microcrystallites (zero-dimensional systems) and some quasi-two-dimensional systems , 1993 .

[197]  Wee‐Jun Ong.  2D/2D Graphitic Carbon Nitride (g-C3N4) Heterojunction Nanocomposites for Photocatalysis: Why Does Face-to-Face Interface Matter? , 2017, Front. Mater..

[198]  Yi Xie,et al.  Fabrication of flexible and freestanding zinc chalcogenide single layers , 2012, Nature Communications.

[199]  J. Coleman,et al.  Liquid Exfoliation of Layered Materials , 2013, Science.

[200]  Y. Chen,et al.  Porous BN/TiO2 hybrid nanosheets as highly efficient visible-light-driven photocatalysts , 2017 .

[201]  Hongyang Liu,et al.  Efficient band structure tuning, charge separation, and visible-light response in ZrS2-based van der Waals heterostructures , 2016 .

[202]  S. Ida,et al.  N doping of oxide nanosheets. , 2009, Journal of the American Chemical Society.

[203]  Hua Zhang,et al.  The chemistry of two-dimensional layered transition metal dichalcogenide nanosheets. , 2013, Nature chemistry.

[204]  B. Pan,et al.  Freestanding atomically-thin cuprous oxide sheets for improved visible-light photoelectrochemical water splitting , 2014 .

[205]  Andras Kis,et al.  Stretching and breaking of ultrathin MoS2. , 2011, ACS nano.

[206]  A. Fujishima,et al.  Electrochemical Photolysis of Water at a Semiconductor Electrode , 1972, Nature.

[207]  A. Splendiani,et al.  Emerging photoluminescence in monolayer MoS2. , 2010, Nano letters.

[208]  Frank E. Osterloh,et al.  Quantum confinement controls photocatalysis: a free energy analysis for photocatalytic proton reduction at CdSe nanocrystals. , 2013, ACS nano.

[209]  Hui-Ming Cheng,et al.  Increasing the Visible Light Absorption of Graphitic Carbon Nitride (Melon) Photocatalysts by Homogeneous Self‐Modification with Nitrogen Vacancies , 2014, Advanced materials.

[210]  M. Antonietti,et al.  A metal-free polymeric photocatalyst for hydrogen production from water under visible light. , 2009, Nature materials.

[211]  Yi Luo,et al.  Single‐Atom Pt as Co‐Catalyst for Enhanced Photocatalytic H2 Evolution , 2016, Advanced materials.

[212]  Quan-hong Yang,et al.  Holey Graphitic Carbon Nitride Nanosheets with Carbon Vacancies for Highly Improved Photocatalytic Hydrogen Production , 2015 .

[213]  Bin Wang,et al.  Improved photocatalytic activity of few-layer Bi4O5I2 nanosheets induced by efficient charge separation and lower valence position , 2017 .

[214]  Rajeev Ahuja,et al.  Strain Engineering for Phosphorene: The Potential Application as a Photocatalyst , 2014 .

[215]  K. Domen,et al.  Cobalt-modified porous single-crystalline LaTiO2N for highly efficient water oxidation under visible light. , 2012, Journal of the American Chemical Society.

[216]  Liangbing Hu,et al.  Optical transmission enhacement through chemically tuned two-dimensional bismuth chalcogenide nanoplates , 2014, Nature Communications.

[217]  Yuen Hong Tsang,et al.  Two-dimensional nanomaterials for photocatalytic CO2 reduction to solar fuels , 2017 .

[218]  J. Zou,et al.  2D Porous TiO2 Single‐Crystalline Nanostructure Demonstrating High Photo‐Electrochemical Water Splitting Performance , 2018, Advanced materials.

[219]  Frank E. Osterloh,et al.  Photocatalytic Water Splitting with Suspended Calcium Niobium Oxides: Why Nanoscale is Better than Bulk − A Kinetic Analysis , 2012 .

[220]  F. Chang,et al.  Enhanced photocatalytic performance of g-C3N4 nanosheets–BiOBr hybrids , 2014 .

[221]  Xiaofeng Yang,et al.  Single-atom catalysis of CO oxidation using Pt1/FeOx. , 2011, Nature chemistry.

[222]  Xinglong Wu,et al.  Enhanced Photocatalytic Oxygen Evolution by Crystal Cutting , 2013, Advanced materials.

[223]  R. Ruoff,et al.  Graphene, related two-dimensional crystals, and hybrid systems for energy conversion and storage , 2015, Science.

[224]  S. Martin,et al.  Environmental Applications of Semiconductor Photocatalysis , 1995 .

[225]  Yi Luo,et al.  Atomic-Layer-Confined Doping for Atomic-Level Insights into Visible-Light Water Splitting. , 2015, Angewandte Chemie.

[226]  W. Chu,et al.  Engineering the electronic structure of two-dimensional subnanopore nanosheets using molecular titanium-oxide incorporation for enhanced photocatalytic activity† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c5sc03551a , 2015, Chemical science.

[227]  Ling Wu,et al.  Ultrathin HNbWO6 nanosheets: facile synthesis and enhanced hydrogen evolution performance from photocatalytic water splitting. , 2015, Chemical communications.

[228]  Jinlong Yang,et al.  Two-dimensional van der Waals nanocomposites as Z-scheme type photocatalysts for hydrogen production from overall water splitting , 2016 .

[229]  K. Loh,et al.  Two-dimensional dichalcogenides for light-harvesting applications , 2015 .

[230]  Hua-ming Li,et al.  Construction of ultrathin C3N4/Bi4O5I2 layered nanojunctions via ionic liquid with enhanced photocatalytic performance and mechanism insight , 2016 .

[231]  G. Xu,et al.  Fabrication and Properties of a Free-Standing Two-Dimensional Titania. , 2017, Journal of the American Chemical Society.

[232]  Yong Jiang,et al.  Pits confined in ultrathin cerium(IV) oxide for studying catalytic centers in carbon monoxide oxidation , 2013, Nature Communications.

[233]  Lukas M. Thulin,et al.  Calculations of strain-modified anatase TiO 2 band structures , 2008 .

[234]  T. Sasaki,et al.  Photocatalyst of lamellar aggregates of RuOx-loaded perovskite nanosheets for overall water splitting. , 2005, The journal of physical chemistry. B.

[235]  M. Wörle,et al.  Gram-scale synthesis of two-dimensional polymer crystals and their structure analysis by X-ray diffraction. , 2014, Nature chemistry.

[236]  Haiquan Xie,et al.  Thickness-ultrathin and bismuth-rich strategies for BiOBr to enhance photoreduction of CO2 into solar fuels , 2016 .

[237]  Di Wu,et al.  Single-crystalline, ultrathin ZnGa(2)O(4) nanosheet scaffolds to promote photocatalytic activity in CO(2) reduction into methane. , 2014, ACS applied materials & interfaces.

[238]  Qun Wei,et al.  Strain-engineered direct-indirect band gap transition and its mechanism in two-dimensional phosphorene , 2014 .

[239]  O. C. Compton,et al.  Niobate Nanosheets as Catalysts for Photochemical Water Splitting into Hydrogen and Hydrogen Peroxide , 2009 .

[240]  Qiyuan He,et al.  Recent Advances in Ultrathin Two-Dimensional Nanomaterials. , 2017, Chemical reviews.

[241]  T. Mueller,et al.  Solar-energy conversion and light emission in an atomic monolayer p-n diode. , 2013, Nature Nanotechnology.

[242]  M. Nasilowski,et al.  Two-Dimensional Colloidal Nanocrystals. , 2016, Chemical reviews.

[243]  Ziwei Li,et al.  Plasmonics of 2D Nanomaterials: Properties and Applications , 2017, Advanced science.

[244]  Pingwu Du,et al.  Hydrogen production on a hybrid photocatalytic system composed of ultrathin CdS nanosheets and a molecular nickel complex. , 2015, Chemistry.

[245]  S. Ida.  Development of Light Energy Conversion Materials Using Two-Dimensional Inorganic Nanosheets , 2015 .