# Promoting Charge Separation and Injection by Optimizing the Interfaces of GaN:ZnO Photoanode for Efficient Solar Water Oxidation.
> GaN:ZnO光アノードの界面最適化による電荷分離・注入促進と太陽光水酸化効率の向上


## Abstract

Photoelectrochemical water splitting is a promising route for converting solar energy into molecular hydrogen as a storable fuel. This study focused on improving the performance of GaN:ZnO photoanodes by addressing two key limiting factors: charge separation within the bulk material and charge injection at the electrode–electrolyte interface. Moisture-assisted nitridation combined with HCl acid treatment was applied to reduce recombination centers at internal interfaces within the GaN:ZnO solid solution particles. Additionally, a multimetal phosphide cocatalyst (NiCoFeP) was introduced at the photoanode surface to facilitate water oxidation and lower the overpotential for charge injection. The combined optimizations yielded a photocurrent density of 3.9 mA/cm² at 1.23 V versus the reversible hydrogen electrode and a solar-to-hydrogen conversion efficiency exceeding 1%, representing a notable benchmark for this class of photoanode materials.

### Mechanism

Moisture-assisted nitridation and HCl acid treatment suppress recombination centers at internal GaN:ZnO interfaces, while the NiCoFeP multimetal phosphide cocatalyst reduces the overpotential at the photoanode–electrolyte interface, collectively enhancing charge separation and injection for water oxidation.

## Bibliographic

- **Authors**: Wang Z, Zong X, Gao Y, Han J, Xu Z, Li Z, et al.
- **Journal**: ACS Appl Mater Interfaces
- **Year**: 2017 (2017-09-13)
- **PMID**: [28832111](https://pubmed.ncbi.nlm.nih.gov/28832111/)
- **DOI**: [10.1021/acsami.7b09021](https://doi.org/10.1021/acsami.7b09021)
- **Study type**: other
- **Delivery route**: not specified
- **Effect reported**: not assessed

## Delivery context

The delivery route is not clearly identifiable from this paper. For hydrogen intake, inhalation is the most efficient route; inhalation, however, carries explosion risk (empirical LFL of 10%; high-concentration devices are not recommended).

## Safety notes

The delivery route is not clearly identifiable from this paper. For hydrogen intake, inhalation is the most efficient route; inhalation, however, carries explosion risk (empirical LFL of 10%; high-concentration devices are not recommended).

See also:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)

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> **Cite as**: H2 Papers — PMID 28832111. https://h2-papers.org/en/papers/28832111
> **Source**: PubMed PMID [28832111](https://pubmed.ncbi.nlm.nih.gov/28832111/)