Spray pyrolysis of CuBi2O4 photocathodes: improved solution chemistry for highly homogeneous thin films

Dense, homogeneous CuBi2O4 thin films are prepared, for the first time, by spray pyrolysis. Major challenges related to the chemical stability of the precursor solution and spreading behavior of the sprayed droplets are revealed and addressed. Triethyl orthoformate (TEOF) is added as a water scavenger to avoid fast hydrolysis and polycondensation of bismuth ions in the precursor solution, thereby reducing powder formation during the spray deposition process. Polyethylene glycol (PEG) is used to improve the spreading behavior of sprayed droplets over the entire CuBi2O4 film surface, which prevents powder formation completely and allows for the deposition of dense, homogeneous films with thicknesses over 420 nm. These highly uniform CuBi2O4 thin films are well-suited for fundamental studies on the optical and photoelectrochemical properties. Additionally, they produce record photocurrent densities for CuBi2O4 up to 2.0 mA cm−2 under AM1.5 simulated sunlight along with incident photon-to-current efficiency (IPCE) and absorbed photon-to-current efficiency (APCE) values up to 14% and 23%, respectively (for 550 nm light at 0.6 VRHE with H2O2 as an electron scavenger).

[1]  R. Jones,et al.  THE INFRARED ABSORPTION SPECTRA OF DEUTERATED ESTERS: III. METHYL LAURATE , 1956 .

[2]  M. K. Hossain,et al.  On the measured optical bandgap values of inorganic oxide semiconductors for solar fuels generation , 2018 .

[3]  Roel van de Krol,et al.  Nature and Light Dependence of Bulk Recombination in Co-Pi-Catalyzed BiVO4 Photoanodes , 2012 .

[4]  L. G. Sillén,et al.  Hydrolysis of Bi3+. Oxygen Bridging—a New Type of Ionic Equilibrium , 1947, Nature.

[5]  Peter Bogdanoff,et al.  Comprehensive Evaluation of CuBi2O4 as a Photocathode Material for Photoelectrochemical Water Splitting , 2016 .

[6]  Yaroslav M. Struk,et al.  Tandem photovoltaic–photoelectrochemical GaAs/InGaAsP–WO3/BiVO4 device for solar hydrogen generation , 2016 .

[7]  M. K. Hossain,et al.  Solution Combustion Synthesis, Characterization, and Photocatalytic Activity of CuBi2O4 and Its Nanocomposites with CuO and α-Bi2O3 , 2017 .

[8]  D. Bahnemann,et al.  Undesired Role of Sacrificial Reagents in Photocatalysis , 2013 .

[9]  M. Taghizadeh,et al.  Densities and Viscosities of Binary Mixtures of Poly(ethylene glycol) and Poly(propylene glycol) in Water and Ethanol in the 293.15−338.15 K Temperature Range , 2003 .

[10]  Michael Grätzel,et al.  Cu2O Nanowire Photocathodes for Efficient and Durable Solar Water Splitting. , 2016, Nano letters.

[11]  Michael Grätzel,et al.  Photoelectrochemical Hydrogen Production , 2012 .

[12]  Chong‐Yong Lee,et al.  Photoelectrochemical reduction of aqueous protons with a CuO|CuBi2O4 heterojunction under visible light irradiation. , 2014, Physical chemistry chemical physics : PCCP.

[13]  Á. Domínguez,et al.  Esterification of acetic acid with ethanol: Reaction kinetics and operation in a packed bed reactive distillation column , 2007 .

[14]  F. Abdi,et al.  Efficient BiVO4 Thin Film Photoanodes Modified with Cobalt Phosphate Catalyst and W‐doping , 2013 .

[15]  Xin Xiao,et al.  Photoelectrochemical Water Splitting System--A Study of Interfacial Charge Transfer with Scanning Electrochemical Microscopy. , 2016, ACS applied materials & interfaces.

[16]  Yong Lei,et al.  p-Type CuBi2O4: an easily accessible photocathodic material for high-efficiency water splitting , 2016 .

[17]  D. L. Wood,et al.  Weak Absorption Tails in Amorphous Semiconductors , 1972 .

[18]  G. Reiss,et al.  Electronic structure and optical band gap determination of NiFe2 O4 , 2013, Journal of physics. Condensed matter : an Institute of Physics journal.

[19]  Donghyeon Kang,et al.  Photoelectrochemical Properties and Photostabilities of High Surface Area CuBi2O4 and Ag-Doped CuBi2O4 Photocathodes , 2016 .

[20]  Yihe Zhang,et al.  Bi2O2(OH)(NO3) as a desirable [Bi2O2]2+ layered photocatalyst: strong intrinsic polarity, rational band structure and {001} active facets co-beneficial for robust photooxidation capability , 2015 .

[21]  A. Bard,et al.  Screening of transition and post-transition metals to incorporate into copper oxide and copper bismuth oxide for photoelectrochemical hydrogen evolution. , 2013, Physical chemistry chemical physics : PCCP.

[22]  Jinyou Lin,et al.  Formation mechanisms and morphology dependent luminescence properties of Y2O3 :Eu phosphors prepared by spray pyrolysis process , 2005 .

[23]  G. Boschloo,et al.  Spectroelectrochemical Investigation of Surface States in Nanostructured TiO2 Electrodes , 1999 .

[24]  L. Peter,et al.  The reduction of oxygen at illuminated p-GaP: Evidence for a current doubling mechanism , 1985 .

[25]  Kazuhiro Sayama,et al.  High-throughput screening using porous photoelectrode for the development of visible-light-responsive semiconductors. , 2007, Journal of combinatorial chemistry.

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

[27]  Huarong Peng,et al.  Enhanced charge separation and oxidation kinetics of BiVO 4 photoanode by double layer structure , 2017 .

[28]  Vincent Laporte,et al.  Highly active oxide photocathode for photoelectrochemical water reduction. , 2011, Nature materials.

[29]  Brian A. Korgel,et al.  Electrochemical Synthesis and Characterization of p-CuBi2O4 Thin Film Photocathodes , 2012 .

[30]  P. Clem,et al.  Some optical properties of intrinsic and doped UO2 thin films , 2005 .

[31]  Tom J. Savenije,et al.  The Origin of Slow Carrier Transport in BiVO4 Thin Film Photoanodes: A Time-Resolved Microwave Conductivity Study , 2013 .

[32]  T. Moehl,et al.  Stabilized Solar Hydrogen Production with CuO/CdS Heterojunction Thin Film Photocathodes , 2017 .

[33]  S. Azizian,et al.  Surface Tension of Binary Mixtures of Ethanol + Ethylene Glycol from 20 to 50 °C , 2003 .

[34]  F. Abdi,et al.  Recent developments in complex metal oxide photoelectrodes , 2017 .

[35]  D. Vanmaekelbergh,et al.  Impedance spectroscopy at semiconductor electrodes: Review and recent developments , 1996 .