Efficient Photoelectrochemical Water Oxidation over Hydrogen‐Reduced Nanoporous BiVO4 with Ni–Bi Electrocatalyst. Issue 9 (28th May 2015)

• Record Type: Journal Article
• Authors: Gan, Jiayong; Lu, Xihong; Rajeeva, Bharath Bangalore; Menz, Ryan; Tong, Yexiang; Zheng, Yuebing
• Is Part Of: ChemElectroChem. Volume 2:Issue 9(2015)
• Page Start: 1385
• Page End: 1395
• Publication Date: 2015-05-28
• Subjects: Electrochemistry -- Periodicals; 541.37
• DOI: 10.1002/celc.201500091
• Languages: English
• ISSNs: 2196-0216

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>BiVO<sub>4</sub> is one of the most promising candidates for photoanodes in solar water splitting. However, the poor charge‐separation yield in BiVO<sub>4</sub> has limited its photochemical activity. Here, we overcome this limitation by constructing a nanoporous morphology that effectively inhibits bulk carrier recombination as well as undergoes controlled introduction of oxygen vacancies through hydrogenation. In comparison to pristine BiVO<sub>4</sub>, hydrogen‐treated BiVO<sub>4</sub> (H‐BiVO<sub>4−<italic>x</italic></sub>) exhibits a superior photocurrent and electron‐hole separation yield, owing to enhanced carrier density and conductivity. In addition, we adopt a layer of nickel–borate (Ni–B<sub>i</sub>) complex on the H‐BiVO<sub>4−<italic>x</italic></sub> surface as an oxygen evolution catalyst to improve the water oxidation kinetics. The Ni–B<sub>i</sub>/H‐BiVO<sub>4−<italic>x</italic></sub> photoanode results in a large cathodic shift (350 mV) in the onset potential for water oxidation at pH 9. Moreover, the photoanodes exhibit high performance in the low‐bias regime and achieve a maximum power point of 0.82 % (photon‐to‐current efficiency) for solar water oxidation at potentials as low as 0.79 V versus RHE with a photocurrent of 2.26 mA cm<sup>−2</sup>. We attribute these improved photoelectrochemical performances to the enhanced charge separation, higher carrier density, better conductivity of H‐BiVO<sub>4−<italic>x</italic></sub>, and the role of Ni–B<sub>i</sub> as a hole conductor, facilitating photogenerated electron mobilization.</p> </abstract>