Efficient direct solar-to-hydrogen conversion by in situ interface transformation of a tandem structure

Abstract

Photosynthesis is nature's route to convert intermittent solar irradiation into storable energy, while its use for an industrial energy supply is impaired by low efficiency. Artificial photosynthesis provides a promising alternative for efficient robust carbon-neutral renewable energy generation. The approach of direct hydrogen generation by photoelectrochemical water splitting utilizes customized tandem absorber structures to mimic the Z-scheme of natural photosynthesis. Here a combined chemical surface transformation of a tandem structure and catalyst deposition at ambient temperature yields photocurrents approaching the theoretical limit of the absorber and results in a solar-to-hydrogen efficiency of 14%. The potentiostatically assisted photoelectrode efficiency is 17%. Present benchmarks for integrated systems are clearly exceeded. Details of the in situ interface transformation, the electronic improvement and chemical passivation are presented. The surface functionalization procedure is widely applicable and can be precisely controlled, allowing further developments of high-efficiency robust hydrogen generators.

Enhancing Charge Carrier Lifetime in Metal Oxide Photoelectrodes through Mild Hydrogen Treatment

“…[7][8][9] However, the cost of these photoelectrodes is likely to be prohibitive, and most of them suffer from instability in aqueous solutions. In contrast, metal oxide semiconductors are relatively cheap and stable in aqueous solutions, but photoelectrodes based on metal oxides have only shown moderate efficiencies (< 8%).…”

Perspectives on the photoelectrochemical storage of solar energy

“…Although the active areas are typically small, <0.5 cm 2 , impressive efficiencies (up to 14%) and lifetimes of up to several days have been reached. 3,27 These devices are still in an early stage of development and so, it is yet unknown whether they can provide Figure 2. Left: Schematic drawing of the system showing the concept for solar collection and conversion to electricity and stored heat.…”

“…One example is a 64 cm 2 modular demonstrator based on triple-junction silicon cells with an efficiency of 3.9% and a lifetime of more than 40 h. 2 PV-driven devices based on III-V semiconductors show higher efficiencies but are more expensive and do not have a scalable design. 3 At the other end of the spectrum are oxide-based devices, which can be cheap but show poor efficiencies. 4 Further development of these preprototype systems is needed as a precursor to the required industrial level scale-up to enable solar fuels to have a real impact.…”

Photocatalytic Water Oxidation on ZnO: A Review

“…The innovation by Fujishima and Honda Laboratories produced the first viable PEC water-splitting cell with an approximate quantum efficiency of 0.1%. To date, solar-to-H 2 (STH) efficiencies of 12.7% have been achieved using a p-GaInP 2 /GaAs electrode as photoanode [6], and the record has only recently been surpassed at 14% using a Z-scheme tandem cell comprised of Rh-functionalized AlInPO x photocathode and RuO 2 as photoanode [7].…”