Unlocking the photocatalytic overall water splitting ability of indium sulfide to produce H2 and H2O2

Photocatalytic overall water splitting (OWS) for H2 and H2O2 production without sacrificial agents is an appealing strategy to realize solar energy conversion. In order to realize photocatalytic OWS, it is necessary for materials to simultaneously satisfy thermodynamic and kinetic requirements, limiting the available selection scope of materials. Therefore, unlocking the potential of these materials that partially fulfill the requirements for photocatalytic overall water splitting would significantly expand the range of material choices. Here, taking In2S3 as an example, we successfully unlocked the OWS potential through a size-dependent strategy, which is based on quantum confinement effect. By adjusting its size to 2.25 nm, it can exhibit impressive photocatalytic OWS activity with the H2 and H2O2 generation rate of ∼42.17 μmol∙g−1∙h−1 and ∼38.65 μmol∙g−1∙h−1, respectively. This work provides a simple strategy to expand the range of materials selection for H2 and H2O2 production from photocatalytic OWS.