Freestanding atomically-thin cuprous oxide sheets for improved visible-light photoelectrochemical water splitting

Atomically-thin sheet is a new class of two-dimensional materials that bring a wide range of extraordinary properties. However, the lack of intrinsic growth anisotropy makes the synthesis of atomically-thin non-layered materials a great challenge. Here, a versatile rapid-heating strategy is proposed and applied, in which the lamellar hybrid intermediate transforms into the clean and freestanding atomically-thin non-layered Cu2O sheet with 4 atomic thicknesses at 300°C in less than 8min. Taking advantage of efficient visible-light harvesting, improved carrier density, and fast interfacial charge transfer as well as facile electrochemical reactions, the ultrathin Cu2O sheets-based photoelectrode yields a photocurrent density up to 3.98mAcm−2, 36 times higher than that of bulk counterpart. Also, the photoelectrode reaches a visible-light-conversion-efficiency of 26.2% that is superior to most existing reports. The rapid-heating strategy guarantees the full exfoliation of lamellar hybrid intermediate into ultrathin Cu2O sheets with the removal of organic component, opening a new way to produce atomically-thin non-layered materials and holding great promise in the applications of visible-light photoelectrochemical water splitting.