Characterization and Optimization of Silver-Modified In_0.2Cd_0.8S-Based Photocatalysts

Area of Science:

• Materials Science
• Photocatalysis
• Electrochemistry

Background:

• Developing efficient photocatalysts is crucial for photoelectrochemical reactions.
• Indium cadmium sulfide (InCdS) is a promising material, but its efficiency needs improvement.
• Doping is a common strategy to enhance semiconductor photocatalyst performance.

Purpose of the Study:

• To screen various metal-doped InCdS photocatalysts for photoelectrochemical applications.
• To investigate the effect of silver (Ag) doping on the properties of In_0.2Cd_0.8S.
• To understand the mechanism behind the enhanced photocatalytic activity.

Main Methods:

• Scanning electrochemical microscopy was employed to screen photocatalyst arrays.
• Fabrication of Ag-doped In_0.2Cd_0.8S electrodes (Ag_0.3(In_0.2Cd_0.8)_0.7S).
• Measurement of photocurrents under UV-visible and visible light, incident photo-to-current conversion efficiency, and Mott-Schottky analysis.

Main Results:

• The Ag_0.3(In_0.2Cd_0.8)_0.7S electrode exhibited the highest photocurrent (1 mA/cm² under UV-visible, 0.53 mA/cm² under visible light).
• Incident photo-to-current conversion efficiencies reached 64% (at 450 nm) for Ag_0.3(In_0.2Cd_0.8)_0.7S and 57% (at 400 nm) for In_0.2Cd_0.8S.
• Mott-Schottky analysis indicated flat-band potentials of -0.55 V for Ag_0.3(In_0.2Cd_0.8)_0.7S and -0.85 V for In_0.2Cd_0.8S.

Conclusions:

• Silver doping significantly enhances the photoelectrochemical performance of InCdS.
• The improved activity of Ag_0.3(In_0.2Cd_0.8)_0.7S is attributed to its high crystallinity, efficient charge separation, and reduced charge recombination.
• The formation of a heterojunction between Ag_0.3(In_0.2Cd_0.8)_0.7S and Ag₂S plays a key role in its superior photocatalytic properties.