Porous Ga<sub>2</sub>O<sub>3</sub> Nanotubes Derived from Urease‐Mediated Interfacially‐Grown NH<sub>4</sub>Ga(OH)<sub>2</sub>CO<sub>3</sub> for High‐Efficient Hydrogen Evolution
Ting Wang, Zhengwu Wang, Ye Zhang, Xiaoting Yang, Yi‐Zhou Zhu, He‐Fang Wang
Abstract
Abstract The authors proposed a novel template‐free strategy, urease‐mediated interfacial growth of NH 4 Ga(OH) 2 CO 3 nanotubes at 20–50 °C, to fabricate the porous Ga 2 O 3 nanotubes. The subtlety of the proposed strategy is all the products from urea enzymolysis are utilized in formation of NH 4 Ga(OH) 2 CO 3 precipitates, and the key for interfacial growth of NH 4 Ga(OH) 2 CO 3 nanotubes is the dynamic match between the rate of CO 2 bubble fusion and NH 4 Ga(OH) 2 CO 3 precipitation. The proposed strategy works well for the doped porous Ga 2 O 3 nanotubes. As a proof‐of‐concept, the porous β‐Ga 2 O 3 and β‐Ga 2 O 3 :Cr 0.001 nanotubes are used as photocatalysts or co‐catalysts with Pt, for H 2 evolution from water splitting. The H 2 evolution rate of porous β‐Ga 2 O 3 nanotubes reach 39.3 mmol g −1 h −1 with solar‐to‐hydrogen (STH) conversion efficiency of 2.11% (Hg lamp) or 498 µmol g −1 h −1 with STH of 0.03% (Xe lamp) respectively, both about 3 times of β‐Ga 2 O 3 nanoparticles synthesized at pH 9.0 without urease. The Cr‐doping enhances the in‐the‐dark H 2 evolution rate pre‐lighted by Hg lamp, and Pt co‐catalysis further elevates the H 2 evolution rate, for instance, the H 2 evolution rate of Pt‐loaded β‐Ga 2 O 3 :Cr 0.001 nanotubes reaches 54.7 mmol g −1 h −1 with STH of 2.94% under continuous lighting of Hg lamp and 1062 µmol g −1 h −1 in‐the‐dark.