Shape-controlled synthesis of well-dispersed platinum nanocubes supported on graphitic carbon nitride as advanced visible-light-driven catalyst for efficient photoreduction of hexavalent chromium.

Photocatalytic degradation of environmental pollutants by using semiconductor-based photocatalysts offers great potential for remediation of toxic chemicals. For an economical and eco-friendly method to eliminate hexavalent chromium (Cr(VI)), favourable catalysts own high efficiency, stability and capability of harvesting light. Combination of metal with semiconductor is a promising route to improve the photocatalytic performance for Cr(VI) reduction. Herein, well-dispersed platinum (Pt) nanocubes (NCs) were synthesized by a facile one-step hydrothermal method with poly-l-lysine (PLL) as the growth-directing agent, followed by their uniform dispersion on graphitic carbon nitride (g-C3N4). Their morphology, crystal structure, chemical composition, and formation mechanism were mainly characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The hybrid nanocomposite was further explored for photocatalytic reduction of Cr(VI) to trivalent chromium (Cr(III)) under visible light at room temperature, by using formic acid (HCOOH) as a reducing agent, showing great improvement in photocatalytic activity and reusability, outperforming the referenced g-C3N4 and home-made Pt black/g-C3N4 catalysts. The effects of various experimental parameters and the proposed mechanism are discussed in detail.

[1]  G. Fu,et al.  Polyallylamine-directed green synthesis of platinum nanocubes. Shape and electronic effect codependent enhanced electrocatalytic activity. , 2013, Physical chemistry chemical physics : PCCP.

[2]  Dongxue Han,et al.  Efficiently photocatalytic reduction of carcinogenic contaminant Cr (VI) upon robust AgCl:Ag hollow nanocrystals , 2015 .

[3]  Keith P. Johnston,et al.  UV-vis spectroscopic determination of the dissociation constant of bichromate from 160 to 400°C , 1998 .

[4]  Jong‐Min Lee,et al.  Highly efficient reduction of hexavalent chromium on amino-functionalized palladium nanowires , 2015 .

[5]  Bin Zhang,et al.  Recent advances in porous Pt-based nanostructures: synthesis and electrochemical applications. , 2014, Chemical Society reviews.

[6]  Meifang Zhu,et al.  Efficient catalytic reduction of hexavalent chromium using palladium nanoparticle-immobilized electrospun polymer nanofibers. , 2012, ACS applied materials & interfaces.

[7]  F. Sen,et al.  Enhanced electrocatalytic activity and stability of monodisperse Pt nanocomposites for direct methanol fuel cells. , 2018, Journal of colloid and interface science.

[8]  M. Jaroniec,et al.  Preparation and Enhanced Visible-Light Photocatalytic H2-Production Activity of Graphene/C3N4 Composites , 2011 .

[9]  Song Bai,et al.  Grain boundary engineered metal nanowire cocatalysts for enhanced photocatalytic reduction of carbon dioxide , 2017 .

[10]  G. Fu,et al.  Arginine-assisted synthesis and catalytic properties of single-crystalline palladium tetrapods. , 2014, ACS applied materials & interfaces.

[11]  David L. Sedlak,et al.  REDUCTION OF HEXAVALENT CHROMIUM BY FERROUS IRON , 1997 .

[12]  Jianrong Chen,et al.  Simple fabrication of core-shell AuPt@Pt nanocrystals supported on reduced graphene oxide for ethylene glycol oxidation and hydrogen evolution reactions , 2016 .

[13]  Abass Esmaeili,et al.  Chromium (III) Removal and Recovery from Tannery Wastewater by Precipitation Process , 2005 .

[14]  F. Sen,et al.  Highly efficient polymer supported monodisperse ruthenium-nickel nanocomposites for dehydrocoupling of dimethylamine borane. , 2018, Journal of colloid and interface science.

[15]  F. Sen,et al.  Different ligand based monodispersed Pt nanoparticles decorated with rGO as highly active and reusable catalysts for the methanol oxidation , 2017 .

[16]  Wei Chen,et al.  Simple pyrolysis of urea into graphitic carbon nitride with recyclable adsorption and photocatalytic activity , 2011 .

[17]  G. Zou,et al.  Nitrogen-rich carbon nitride hollow vessels: synthesis, characterization, and their properties. , 2010, The journal of physical chemistry. B.

[18]  X. Xia,et al.  A facile approach to the synthesis of highly electroactive Pt nanoparticles on graphene as an anode catalyst for direct methanol fuel cells. , 2010, Chemical communications.

[19]  J. Margrave,et al.  Powder synthesis and characterization of amorphous carbon nitride, a-C3N4 , 2000 .

[20]  Marta I. Litter,et al.  Heterogeneous photocatalysis: Transition metal ions in photocatalytic systems , 1999 .

[21]  G. Fu,et al.  One-pot synthesis of three-dimensional platinum nanochain networks as stable and active electrocatalysts for oxygen reduction reactions , 2012 .

[22]  Ke Dai,et al.  Hydrothermal synthesis of α-Fe2O3/g-C3N4 composite and its efficient photocatalytic reduction of Cr(VI) under visible light , 2015 .

[23]  O. Sadik,et al.  Palladium nanoparticles for catalytic reduction of Cr(VI) using formic acid , 2007 .

[24]  P. Gong,et al.  High-index facet engineering of PtCu cocatalysts for superior photocatalytic reduction of CO2 to CH4 , 2017 .

[25]  Yasuhiro Shiraishi,et al.  Hot-Electron-Induced Highly Efficient O2 Activation by Pt Nanoparticles Supported on Ta2O5 Driven by Visible Light. , 2015, Journal of the American Chemical Society.

[26]  Ai-Jun Wang,et al.  Simple fabrication of AuPd@Pd core-shell nanocrystals for effective catalytic reduction of hexavalent chromium , 2017 .

[27]  Chao Zhou,et al.  Facile Synthesis of g-C3N4 Nanosheets/ZnO Nanocomposites with Enhanced Photocatalytic Activity in Reduction of Aqueous Chromium(VI) under Visible Light , 2016, Nanomaterials.

[28]  Xianhui Wang,et al.  Structural, electronic and optical properties of a hybrid triazine-based graphitic carbon nitride and graphene nanocomposite. , 2015, Physical chemistry chemical physics : PCCP.

[29]  Z. Zou,et al.  Polymeric g-C3N4 Coupled with NaNbO3 Nanowires toward Enhanced Photocatalytic Reduction of CO2 into Renewable Fuel , 2014 .

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

[31]  M. Ojeda,et al.  Formic acid dehydrogenation on au-based catalysts at near-ambient temperatures. , 2009, Angewandte Chemie.

[32]  F. Sen,et al.  Highly efficient monodisperse Pt nanoparticles confined in the carbon black hybrid material for hydrogen liberation. , 2018, Journal of colloid and interface science.

[33]  W. E. Mourad,et al.  Photocatalytic reduction of environmental pollutant Cr(VI) over some semiconductors under UV/visible light illumination , 1998 .

[34]  Xinhua Xu,et al.  Reduction of hexavalent chromium by carboxymethyl cellulose-stabilized zero-valent iron nanoparticles. , 2010, Journal of contaminant hydrology.

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

[36]  W. Ho,et al.  Water-assisted production of honeycomb-like g-C3N4 with ultralong carrier lifetime and outstanding photocatalytic activity. , 2015, Nanoscale.

[37]  F. Sen,et al.  Enhanced electrocatalytic activity and durability of Pt nanoparticles decorated on GO-PVP hybride material for methanol oxidation reaction , 2017 .

[38]  Jiaguo Yu,et al.  Enhanced visible light photocatalytic hydrogen production activity of CuS/ZnS nanoflower spheres , 2015 .

[39]  M. Zahmakiran,et al.  Palladium nanoparticles supported on amine-functionalized SiO2 for the catalytic hexavalent chromium reduction , 2016 .

[40]  A. Samokhin,et al.  XPS study of surface chemistry of tungsten carbides nanopowders produced through DC thermal plasma/hydrogen annealing process , 2015 .

[41]  C. Fan,et al.  Radiation induced reduction: an effective and clean route to synthesize functionalized graphene , 2012 .

[42]  H. Yoneyama,et al.  Heterogeneous photocatalytic reduction of dichromate on n-type semiconductor catalysts , 1979, Nature.

[43]  Ai-Jun Wang,et al.  Theophylline-assisted, eco-friendly synthesis of PtAu nanospheres at reduced graphene oxide with enhanced catalytic activity towards Cr(VI) reduction. , 2017, Journal of colloid and interface science.

[44]  Harry B Gray,et al.  Powering the planet with solar fuel. , 2009, Nature chemistry.

[45]  Yuxin Yang,et al.  Preparation and enhanced visible-light photocatalytic activity of silver deposited graphitic carbon nitride plasmonic photocatalyst , 2013 .

[46]  W. Qi,et al.  Reduction of Hexavalent Chromium Using Recyclable Pt/Pd Nanoparticles Immobilized on Procyanidin-Grafted Eggshell Membrane , 2014 .

[47]  Rose Amal,et al.  Hybrid graphene and graphitic carbon nitride nanocomposite: gap opening, electron-hole puddle, interfacial charge transfer, and enhanced visible light response. , 2012, Journal of the American Chemical Society.

[48]  Qiang Xu,et al.  Catalytic chromium reduction using formic acid and metal nanoparticles immobilized in a metal-organic framework. , 2013, Chemical communications.

[49]  Yujing Li,et al.  AuPd bimetallic nanoparticles decorated graphitic carbon nitride for highly efficient reduction of water to H2 under visible light irradiation , 2015 .

[50]  G. Stucky,et al.  Carbon nitride supported AgPd alloy nanocatalysts for dehydrogenation of formic acid under visible light , 2017 .

[51]  H. Jónsson,et al.  Origin of the Overpotential for Oxygen Reduction at a Fuel-Cell Cathode , 2004 .

[52]  W. Choi,et al.  Simultaneous and synergistic conversion of dyes and heavy metal ions in aqueous TiO2 suspensions under visible-light illumination. , 2005, Environmental science & technology.

[53]  B. K. Dutta,et al.  Photo-reduction of hexavalent chromium in aqueous solution in the presence of zinc oxide as semiconductor catalyst. , 2009 .

[54]  Thomas Härtling,et al.  Monodisperse platinum nanospheres with adjustable diameters from 10 to 100 nm: synthesis and distinct optical properties. , 2008, Nano letters.

[55]  Yuehong Su,et al.  A comprehensive review of Pt electrocatalysts for the oxygen reduction reaction: Nanostructure, activity, mechanism and carbon support in PEM fuel cells , 2017 .

[56]  F. Sen,et al.  Carbon-nanotube-based rhodium nanoparticles as highly-active catalyst for hydrolytic dehydrogenation of dimethylamineborane at room temperature. , 2018, Journal of colloid and interface science.

[57]  Jiaguo Yu,et al.  Dye-sensitized solar cells based on anatase TiO 2 hollow spheres/carbon nanotube composite films , 2011 .

[58]  Jaekyung Yoon,et al.  Application of immobilized nanotubular TiO(2) electrode for photocatalytic hydrogen evolution: reduction of hexavalent chromium (Cr(VI)) in water. , 2009, Journal of hazardous materials.