Over 14% unassisted water splitting driven by immersed perovskite/Si tandem photoanode with Ni-based catalysts

Perovskite-based photovoltaic systems are at the forefront of innovative methods to facilitate solar fuel generation, particularly H 2 generation via overall water splitting, thanks to their high photovoltage and potential for substantial solar-to-hydrogen (STH) efficiency. Despite successful encapsulation strategies employed in solar cells to enable the practical implementation of perovskite materials, the stability of perovskite-based photoelectrodes remains a significant bottleneck, restricting viable H 2 production. Moreover, the intricate electrical connections and reliance on expensive noble metals hinder the pursuit of cost-effective H 2 production using perovskite-based devices. In this study, we introduce a dual-absorber perovskite/Si tandem structure encapsulated with a NiFe alloy catalyst grown on Ni foil to create a monolithic photoanode. This designed photoanode yielded a photocurrent of 14.21 mA cm −2 at 1.23 V versus RHE, complemented by an onset potential of −0.5 V in an alkaline electrolyte. When combined with a cathode comprised of Ni nanowires (with a mere 46 mV overpotential at 10 mAcm −2 ), the system maintained a sustained overall water splitting reaction for 45 h, achieving a stand-alone STH efficiency exceeding 14%. This pioneering dual-absorber stand-alone PEC system represents a significant step towards minimizing losses and outstripping conventional tandem PV-PEC, series PV-PEC, and series PEC configurations in terms of performance, practicality, and cost-effectiveness. • We introduce a dual-absorber perovskite/Si tandem structure with a NiFe alloy catalyst on Ni foil for a monolithic photoanode. • The photoanode shows promising performance with 14.21 mA cm −2 saturation photocurrent density. • It achieves −0.5 V vs RHE onset potential and 14.86% applied-bias photon-to-current conversion efficiency in alkaline media. • The system sustained water splitting for 45 h, achieving stand-alone solar-to-hydrogen efficiency exceeding 14%.