The ability to regulate charge separation is pivotal for obtaining high efficiency of any photoelectrode used for solar fuel production. Vacancy engineering for metal oxide semiconductor photoelectrode is a major strategy but has faced a formidable challenge in bulk charge transport because of the elusive charge self‐trapping site. In this work, a new deep eutectic solvent to engineer bismuth vacancies (Bivac) of BiVO4 photoanode is reported; the novel Bivac can remarkably increase the charge diffusion coefficient by 5.8 times (from 1.82 × 10−7 to 1.06 × 10−6 cm2 s−1), which boosts the charge transport efficiency. Through further loading CoBi cocatalyst to enhance charge transfer efficiency, the photocurrent density of BiVO4 photoanode with optimal Bivac concentration reaches 4.5 mA cm−2 at 1.23 V vs reversible hydrogen electrode under AM 1.5 G illumination, which is higher than that of previously reported Ovac engineered BiVO4 photoanode where the BiVO4 photoanode is synthesized by a similar procedure. This work perfects a cation defect engineering that enables the potential capability to equate the charge transport properties in different types of semiconductor materials for solar fuel conversion.

Ah ost-guest complex self-assembled through Co 2+ and cucurbit[5]uril (Co@CB[5]) is used as as upramolecular catalyst on the surface of metal oxides including porous indium tin oxide (ITO) and porous BiVO 4 for efficient electrochemical and photoelectrochemical water oxidation. When immobilized on ITO, Co@CB[5] exhibited at urnover frequency (TOF) of 9.9 s À1 at overpotential h = 550 mV in ap H9.2 borate buffer. Meanwhile,w hen Co@CB[5] complex was immobilized onto the surface of BiVO 4 semiconductor,t he assembled Co@CB-[5]/BiVO 4 photoanode exhibited al ow onset potential of 0.15 V(vs.R HE) and ah igh photocurrent of 4.8 mA cm À2 at 1.23 V(vs.R HE) under 100 mW cm À2 (AM 1.5) light illumination. Kinetic studies confirmed that Co@CB[5] acts as asupramolecular water oxidation catalyst, and can effectively accelerate interfacial charge transfer between BiVO 4 and electrolyte.S urface charge recombination of BiVO 4 can be also significantly suppressed by Co@CB[5].

N-type silicon is a kind of semiconductor with a narrow band gap that has been reported as an outstanding light-harvesting material for photoelectrochemical (PEC) reactions. Decorating a thin catalyst layer on the n-type silicon surface can provide a direct and effective route toward PEC water oxidation. However, most of catalyst immobilization methods for reported n-type silicon photoanodes have been based on energetically demanding, time-consuming, and high-cost processes. Herein, a high-performance NiFeP alloy (NiFeP)-decorated n-type micro-pyramid silicon array (n-Si) photoanode (NiFeP/n-Si) was prepared by a fast and low-cost electroless deposition method for light-driven water oxidation reaction. The saturated photocurrent density of NiFeP/n-Si can reach up to ∼40 mA cm–2, and a photocurrent density of 15.5 mA cm–2 can be achieved at 1.23 VRHE under light illumination (100 mW cm–2, AM1.5 filter), which is one of the most promising silicon-based photoanodes to date. The kinetic studies showed that the NiFeP on the silicon photoanodes could significantly decrease the interfacial charge recombination between the n-type silicon surface and electrolyte.

No abstract