Enhanced photoelectrochemical CO2 reduction activity towards selective generation of alcohols over CuxO/SrTiO3 heterojunction photocathodes

Photoelectrochemical reduction (PECR) of CO2 to value-added chemicals and fuels will reduce the dependency on fossil fuels, also it will solve environmental issues that arise due to greenhouse gases. A heterojunction of CuxO/SrTiO3 with varying post-annealing temperature ranges from 300 to 600 degrees C (CS300-600) was synthesized by overlying the spin-coated SrTiO3 on electrodeposited Cu2O over the FTO glass substrate. The synthesized photoelectrode's crystallinity and phase formation significantly varied by varying the post-annealing temperature, which was characterized via XRD and Raman spectroscopy. Optical, morphological, type of heterojunction formation and elemental surface oxidation states of photoelectrodes were studied through UV-visible DRS spectrum, FE-SEM, and XPS analysis respectively. Electrocatalytic analysis such as Linear Sweep Voltammetry (LSV), and Electrochemical Impedance Spectrometry (EIS) was employed, thus it conforms to the highest photocurrent density (-1.38 mA/cm(2) at -0.6V vs. Ag/AgCl), and low charge transfer resistance (RCT=0.412 k Omega) at the electrode-electrolyte interfaces for CS500 photoelectrode as compared to others photoelectrodes. PECR of CO2 to liquid product formation was evaluated by applying different potential ranges (0 to -0.6 V vs. Ag/AgCl). Highest methanol formation of 48.69 mu mol.cm(-2)hr(-1), which is approximately 9 times enhanced as compared to the pure Cu2O (5.62 mu mol.cm(-2)hr(-1)) photoelectrode at 0 V vs Ag/AgCl for CS500 heterojunction. Optimization of overlaying SrTiO3 synthesis temperature for crystallization formation on Cu2O and applied photoelectrode potential findings could pave the way for designing other new heterojunction types for selective liquid alcohol production.