Ink-Based CuIn0.3Ga0.7S2 Nanocrystal Thin Films as Photocathodes for Photoelectrochemical CO2 Reduction Reaction

One of the promising methods to solve the current energyand environmentissues is photoelectrochemical (PEC) water splitting and CO2 reduction reaction. Chalcopyrite copper indium gallium sulfide (CIGS)and CuIn0.3Ga0.7S2 nanocrystal thinfilms have been considered photovoltaic materials, and here, we demonstratedtheir potential to reduce CO2 into CO. A modified solutionprocess affords to decrease the number of surface ligands, which triggersan increase in the crystal size and an improved reproducibility inperformance and output current. After depositing gold nanoparticleson the surface of CIGS, the Faradic efficiency related to the CO2-to-CO conversion can reach 12.93% in aqueous electrolytesand 25% in nonaqueous electrolytes. Further investigation points outthat in the range of applied potential between -0.1 and -0.2V vs a reversible hydrogen electrode (RHE), the CIGSphotocathode appears to display a stable photocurrent density for1 h, but when applying a higher applied bias, such as of -0.3V vs RHE, the degradation of the current is significant.Additionally, we found that coupling catalysts to the CIGS increasesthe selectivity toward CO and minimizes the competitive hydrogen evolutionreaction.

Automated summary

Photoelectrochemical water splitting and CO2 reduction reaction is a promising method for addressing energy and environment issues. Research has shown that a modified solution process can enhance crystal size and improve performance and output current by reducing surface ligands. Deposition of gold nanoparticles on CIGS surface can achieve a Faradic efficiency of 12.93% in aqueous electrolytes and 25% in nonaqueous electrolytes for CO2-to-CO conversion. Further investigation reveals that the CIGS photocathode displays stable photocurrent density within a certain applied potential range, but significant current degradation occurs at higher applied bias. Coupling catalysts with CIGS enhances selectivity towards CO and reduces competitive hydrogen evolution reaction.