Reduced graphene oxide grafted on p-Si photocathode as a multifunctional interlayer for enhanced solar hydrogen production

Photoelectrochemical (PEC) water splitting has been intensively studied as a sustainable approach to directly convert intermittent solar energy into storable hydrogen fuels. Its practical application, however, has been tethered by the trade-off between photoelectrode efficiency and stability. Herein, this work demonstrates a facile strategy to design highly efficient and stable Si photocathodes by utilizing the reduced graphene oxide (rGO) as a multifunctional interlayer to bridge the Pt catalysts and p-Si. The covalently grafted rGO layer forms a Schottky junction with p-Si allowing effective charge carrier extraction required for high efficiency, and, simultaneously, protects the Si surface and anchors Pt catalysts with enhanced stability. Consequently, the as-fabricated Pt/rGO/p-Si photocathodes exhibit an impressive PEC performance under simulated AM1.5G illumination with a high applied bias photon-to-current efficiency (ABPE) of 4.9% and stability of over 110 hours, outperforming the Pt/p-Si control sample and state-of-the-art p-Si based photocathodes. In summary, this work offers a viable path for developing high-performance solar-to-fuel conversion devices in the future.