Ion Sputtering–Assisted Double‐Side Interfacial Engineering for CdIn2S4 Photoanode toward Improved Photoelectrochemical Water Splitting

Abstract

AbstractDue to its suitable band energy level and small band gap, CdIn2S4 is a promising photoanode for photoelectrochemical (PEC) water splitting. Nevertheless, the serious charge recombination at the back contact and photoelectrode/electrolyte interface severely hinders its PEC activity. Herein, a facile magnetron ion‐sputtering strategy is adopted to fabricate TiO2 underlayer and NiO overlayer to modify both sides of CdIn2S4 photoanode. The TiO2 underlayer serves as an electron transport layer to promote electrons transfer from CdIn2S4 to fluorine‐doped tin oxide substrate and hinder holes' transportation, thus suppressing the charge recombination at the back contact. NiO, as a p‐type semiconductor, forms a p‐n heterojunction with CdIn2S4, inducing a built‐in electric field to facilitate charge transport. Meanwhile, NiO overlayer acts as a co‐catalyst to enhance surface reaction kinetics, and thereby improves the carrier injection efficiency at photoelectrode/electrolyte interface. As a result, the optimum TiO2/CdIn2S4/NiO photoanode exhibits photocurrent as high as 0.6 mA cm−2 at 1.23 V versus reversible hydrogen electrode, which is about 2.3 times that of bare CdIn2S4. This work provides an effective strategy to manipulate the charge carrier dynamics to improve the PEC activity of photoanode.