Characterization and Optimization of Silver-Modified In0.2Cd0.8S-Based Photocatalysts

In this research, we performed scanning electrochemical microscopy to screen M x (In 0.2 Cd 0.8 ) 1- x S (M = V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Ag, W, Ir, Pt, and Te) photocatalyst arrays for efficient photoelectrochemical reaction. Doping 30% Ag to form the Ag 0.3 (In 0.2 Cd 0.8 ) 0.7 S electrode could result in the highest photocurrent, and also, the anode photocurrents were found to be 1 and 0.53 mA/cm 2 under UV-visible and visible light, respectively, comparatively higher than that of the In 0.2 Cd 0.8 S electrode (0.45 and 0.25 mA/cm 2 ). The highest incident photo-to-current conversion efficiency of the Ag 0.3 (In 0.2 Cd 0.8 ) 0.7 S photocatalyst and In 0.2 Cd 0.8 S were found to be 64% (λ = 450 nm) and 57% (λ = 400 nm), respectively. The Mott-Schottky plots showed that In 0.2 Cd 0.8 S and Ag 0.3 (In 0.2 Cd 0.8 ) 0.7 S photoelectrodes could exhibit a flat-band potential of -0.85 and -0.55 V versus Ag/AgCl, respectively. Based on these findings, the superior photocatalytic activity of the Ag 0.3 (In 0.2 Cd 0.8 ) 0.7 S photoelectrode was mainly attributed to its high crystalline structure for efficient charge separation and reduction of charge recombination in the heterojunction of Ag 0.3 (In 0.2 Cd 0.8 ) 0.7 S and Ag 2 S.