Investigation of water splitting using III‐N structures

Abstract

Specifics of the water photoelectrolysis in KOH‐base aqueous solution using GaN‐based structures as working electrodes are studied. The structures were grown by HVPE and MOCVD techniques on sapphire substrates. In highly Si‐doped HVPE‐grown GaN layers (ND−NA ∼ 3 × 1018 cm−3) a barrier at the E1 offset potential dominates the current–potential (I–E) characteristics. The same dominant E1 offset potential was observed in MOCVD‐grown GaN/InGaN nanopillar structures after the treatment. The Debye screening effect in high‐concentration of KOH electrolyte (20–40 wt.%) that reduces the potential barrier was observed clearly in the defectless nanopillar structures. The corrosion process is initiated in the top p‐type layers via channels associated with threading defects and can penetrate deeply into the structure. It further proceeds in a lateral direction in n‐type layers forming voids and cavities in the structure. The H2 production rate of 0.3–0.6 ml cm−2 h−1 was measured for n‐GaN‐based structure in KOH electrolyte under the Xe‐lamp illumination (concentration factor ×15).

A Novel Approach for Achieving High‐Efficiency Photoelectrochemical Water Oxidation in InGaN Nanorods Grown on Si System: MXene Nanosheets as Multifunctional Interfacial Modifier

“…However, its solar‐to‐hydrogen (STH) efficiency is restricted by the lack of efficient photoanodes 1,2. Recently, the unique integration of photocatalysts and semiconductors, such as, InGaN nanorods and Si, has exhibited bright prospects and made great progress for PEC water oxidation 3–5. First, InGaN nanorods have much higher theoretical maximum STH efficiency of ≈27%, which exceeds most other metal oxides (TiO 2 and WO 3 ) that have been devoted great efforts 6–8.…”

Modulating Surface/Interface Structure of Emerging InGaN Nanowires for Efficient Photoelectrochemical Water Splitting

“…[120][121][122] The integration of efficient photocatalyst (InGaN NWs) and abundant semiconductor (Si) shows a promise for practical PEC water splitting. [109,123,124] Nowadays, InGaN NWs are generally epitaxially grown on Si substrate for solar water splitting. However, the introduced crystal defects of InGaN NWs and poor interface due to the lattice mismatch between InGaN and Si could trap the photogenerated charge carriers, leading to serious charge recombination.…”