In situ engineered Ce2O2S/CeO2 nanofibrous heterojunctions for photocatalytic H2O2 synthesis via S-scheme charge separation

Photocatalytic H2O2 synthesis offers an efficient and sustainable means to convert solar energy into chemical energy, representing a forefront and focal point in photocatalysis. S-scheme heterojunctions demonstrate the capability to effectively separate photogenerated electrons and holes while possessing strong oxidation and reduction abilities, rendering them potential catalysts for photocatalytic H2O2 synthesis. However, designing Sscheme heterojunction photocatalysts with band alignment and close contact remains challenging. Here we report Ce2O2S/CeO2 multiphase nanofibrous prepared via an in situ sulphuration/de-sulphuration strategy. This in situ process enables intimate contact between the two phases, thereby shortening the charge transfer distance and promoting charge separation. The interfacial electronic interaction and charge separation were investigated using in situ X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations. The work function difference enables Ce2O2S to donate electrons to CeO2 upon combination, resulting in the formation of an internal electric field (IEF) at interfaces. This IEF, along with bent energy bands, facilitates the separation and transfer of photogenerated charge carriers via an S-scheme pathway across the Ce2O2S/CeO2 interfaces. The Ce2O2S as the reduction photocatalyst exhibits significant O2 adsorption and activation along with a low energy barrier for the H2O2 production. The optimal Ce2O2S/CeO2 nanofibers heterojunction demonstrate enhanced photocatalytic H2O2 production of 2.91 mmol g- 1h- 1 , 58 times higher than that of pristine CeO2 nanofibers. This investigation provides valuable insights for the rational design and preparation of intimate contact nanofibrous heterojunctions with efficient solar H2O2 synthesis.