Abstract

With the constant consumption of traditional energy sources, it is urgent to explore and develop new energy sources. Photoelectrochemical (PEC) water splitting is a method of preparing energy that can continuously generate hydrogen fuel without pollution to the environment. As an important part of the PEC water splitting system, the choice of semiconductor photoelectrode is crucial. Among these materials, gallium nitride (GaN) has attracted considerable attention due to its tunable band gap, favorable band edge positions, wide band gap, and good stability. In the past years, many reports have been obtained in GaN for PEC water splitting. This review summarizes the GaN as photoelectrodes for PEC water splitting, and methods to improve the efficiency of GaN for PEC water splitting also will be summarized from change morphology, doping, surface modification, and composition of solid solution or multiple-metal incorporation. Eventually, the future research directions and challenges of GaN for PEC water splitting are also discussed.

Highlights

  • Rising energy demand due to population growth has led to the rapid consumption of fossil fuels and serious environmental problems [1]

  • We summarize the recent progress of using gallium nitride (GaN) as photoelectrode for PEC water splitting and enumerate some commonly used strategies to improve the performance of photoelectrode

  • The above structures are expected, and GaN can have nanorods [77], nanocolumns [78], nano-pyramids [79], and so on. It can be known from the above results that changing the morphology of GaN influences the efficiency of PEC water splitting, which mainly affects the light absorption efficiency of GaN and reduces light reflection and loss

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Summary

Introduction

Rising energy demand due to population growth has led to the rapid consumption of fossil fuels and serious environmental problems [1]. PV-E is achieved by connecting the photovoltaic cell and water electrolyzer The advantage of this strategy is its solar-hydrogen conversion efficiency of more than 10%, but it is still too expensive compared to traditional hydrogen production methods [14–18]. The potentially explosive hydrogen-oxygen mixture produced requires expensive equipment for separation to avoid reaction, which greatly increases production costs [19] In this case, PEC provides considerable conversion efficiency at an affordable cost [20, 21]. The carriers that reach the surface of the semiconductor want to trigger an efficient water splitting reaction, which must meet the following requirements. To achieve practical hydrogen production, GaN is still facing many challenges as an excellent photoelectrode material, including how to get a larger reaction area, how to enhance the absorption of light, and how to separate and transport photogenerated carriers more quickly and effectively [49, 50]. We have a brief outlook of GaN for PEC water splitting

PEC cell configurations
Calculation of efficiencies
Surface decoration
GaN material having different morphologies
GaN material having different doping
Composition of solid solution
The multiple-metal incorporation
Conclusion
Findings
Conflict of interest
Full Text
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