Optimization of PEC and photocathodic protection performance of TiO2/CuInS2 heterojunction photoanodes

The establishment of heterojunction is a powerful strategy to enhance the photoresponse performance of photoanode. Here, TiO2/CuInS2 (T/CIS) composites were prepared via a two-step hydrothermal method, and their morphologies were controlled by adjusting the reaction time. The absorption spectra show that CuInS2 can significantly improve the absorption of visible light. The T/CIS2 (2 h reaction time) photoanode exhibited the most outstanding photoelectrochemical (PEC) performance, with a photocurrent density of 168% that of the pure TiO2 photoanode. Under simulated sunlight, this photoanode can supply a protective photocurrent of 0.49 mA cm(-2) and a protective voltage of 0.36 V to stainless steel (304ss), which are about 4 and 2 times those of the TiO2 sample. The enhancement in the photocathodic protection performance is attributed to enlarged visible light absorbance and higher charge separation rate. This study demonstrates that the TiO2/CuInS2 photoanode is a promising candidate for application in photoinduced cathodic protection of metallic materials.