Photocatalytic Overall Water Splitting Reaction Feature on Photodeposited Ni_xP/γ-Ga₂O₃Nanosheets

Abstract

Solar light-driven overall water splitting for hydrogen production is an ideal solution to climate warming and energy shortage issues. Obtaining a highly efficient and stable photocatalyst remains a major challenge at present. Herein, Ni x P/γ-Ga 2 O 3 nanosheets, which were synthesized from NiCl 2 , NaH 2 PO 2 , and home-made γ-Ga 2 O 3 nanosheets by the photodeposition method under 254 UV irradiation for 30 min, are found as a highly active and durable photocatalyst for pure water splitting into H 2 and O 2 without a sacrificial reagent. The H 2 production rate is as high as 5.5 mmol•g −1 •h −1 under 125 W high-pressure mercury lamp irradiation, which is 3.4 and 2.5 times higher than that on the pristine γ-Ga 2 O 3 nanosheets and Pt/γ-Ga 2 O 3 nanosheets, respectively, and is 2.0 times higher than that on the 0.5 wt % Ni 2 P/γ-Ga 2 O 3 reported previously. However, the O 2 evolution rate is much less than the H 2 evolution rate in the initial reaction stage. On prolonging the irradiation time, H 2 evolution declines, while O 2 evolution increases until it reaches its stoichiometric value corresponding to H 2 . The reason for the photocatalytic behavior of Ni x P/γ-Ga 2 O 3 is studied and the corresponding mechanism is suggested. The absent or low oxygen evolution in the initial reaction stage is because the dioxygen generated from water oxidation by the photogenerated holes is wholly or partially captured by the surface oxygen vacancies to form the surface peroxide bonds (−O−O−). Once the oxygen vacancies are eliminated by the photogenerated O 2 , the overall water splitting reaction would reach the steady state. Thereafter, H 2 production decreases from 5.5 to 2.0 mmol•g −1 •h −1 , but the O 2 evolution gradually approaches the corresponding stoichiometric value, especially for the photocatalyst treated with H 2 O 2 for 24 h.

A Review of β-Ga2O3 Power Diodes

“…The FLOSFIA company (Kyoto, Japan) predominantly employs Mist-epitaxy to prepare α-Ga 2 O 3 wafers, and in March 2023, they unveiled an amperage-class 1700 V α-Ga 2 O 3 trench SBD device [45][46][47][48][49]. The cubic spinel structure of γ-Ga 2 O 3 is principally utilized as a photocatalyst for hydrogen production via water splitting [50][51][52][53]. Current research on the cubic perovskite structure of δ-Ga 2 O 3 is comparatively limited.…”

“…Materials 2024, 17, x FOR PEER REVIEW 3 of 34 γ-Ga2O3 is principally utilized as a photocatalyst for hydrogen production via water splitting [50][51][52][53]. Current research on the cubic perovskite structure of δ-Ga2O3 is comparatively limited.…”

Strategies to Improve the Activity of Silver–loaded Calcium Titanate Crystal Photocatalyst for Photocatalytic Reduction of Carbon Dioxide with Water

“…Ga 2 O 3 has been investigated as a good photocatalytic material for water splitting [38] and photocatalytic CO 2 reduction. [39] However, because there are fewer CO 2 reduction sites on the surface, its selectivity for CO production is only 60 % even after loading Ag.…”

Enhancing Photocatalytic Activities for Sustainable Hydrogen Evolution on Structurally Matched CuInS2/ZnIn2S4 Heterojunctions

“…Li et al reported a ZnIn 2 S 4 /CdS hollow core-shell nano-heterostructure with an appropriate potential gradient and Zn/In bimetallic synergism, showing improved carrier transportation properties [19]. Research has revealed that constructing heterojunctions between two or more semiconductors results in the creation of a potential gradient and an internal electric field, which serves as an effective method for the separation of electrons and holes [20,21]. However, previous studies have mainly considered semiconductor bandgap width matching, whose perspective of structural matching has not been investigated as thoroughly.…”