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 CuInS2can 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 TiO2photoanode. Under simulated sunlight, this photoanode can supply a protective photocurrent of 0.49 mA cm-2and a protective voltage of 0.36 V to stainless steel (304ss), which are about 4 and 2 times those of the TiO2sample. 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/CuInS2photoanode is a promising candidate for application in photoinduced cathodic protection of metallic materials.