NiFeOx decorated Ge-hematite/perovskite for an efficient water splitting system

To boost the photoelectrochemical water oxidation performance of hematite photoanodes, high temperature annealing has been widely applied to enhance crystallinity, to improve the interface between the hematite-substrate interface, and to introduce tin-dopants from the substrate. However, when using additional dopants, the interaction between the unintentional tin and intentional dopant is poorly understood. Here, using germanium, we investigate how tin diffusion affects overall photoelectrochemical performance in germanium:tin co-doped systems. After revealing that germanium is a better dopant than tin, we develop a facile germanium-doping method which suppresses tin diffusion from the fluorine doped tin oxide substrate, significantly improving hematite performance. The NiFeOx@Ge-PH photoanode shows a photocurrent density of 4.6mAcm(-2) at 1.23 V-RHE with a low turn-on voltage. After combining with a perovskite solar cell, our tandem system achieves 4.8% solar-to-hydrogen conversion efficiency (3.9mAcm(-2) in NiFeOx@Ge-PH/perovskite solar water splitting system). Our work provides important insights on a promising diagnostic tool for future co-doping system design. Germanium (Ge) has potential as a dopant suitable for the hematite-based photoelectrochemical water splitting system. Here, the authors report the fabrication of Ge doped porous hematite and demonstrate an efficient tandem system of Ge doped porous hematite and the perovskite solar cell.

Automated summary

The study investigates how tin diffusion affects overall photoelectrochemical performance, revealing that germanium is a better dopant for enhancing hematite photoanode performance. A new doping method using germanium suppresses tin diffusion, significantly improving the performance of hematite photoanodes.