Abstract
A BiVO4 photoanode with exposed (040) facets was prepared to enhance its photoelectrochemical performance. The exposure of the (040) crystal planes of the BiVO4 film was induced by adding NaCl to the precursor solution. The as-prepared BiVO4 photoanode exhibits higher solar-light absorption and charge-separation efficiency compared to those of an anode prepared without adding NaCl. To our knowledge, the photocurrent density (1.26 mA cm−2 at 1.23 V vs. RHE) of as-prepared BiVO4 photoanode is the highest according to the reports for bare BiVO4 films under simulated AM1.5G solar light, and the incident photon-to-current conversion efficiency is above 35% at 400 nm. The photoelectrochemical (PEC) water-splitting performance was also dramatically improved with a hydrogen evolution rate of 9.11 μmol cm−2 h−1, which is five times compared with the BiVO4 photoanode prepared without NaCl (1.82 μmol cm−2 h−1). Intensity-modulated photocurrent spectroscopy and transient photocurrent measurements show a higher charge-carrier-transfer rate for this photoanode. These results demonstrate a promising approach for the development of high-performance BiVO4 photoanodes which can be used for efficient PEC water splitting and degradation of organic pollutants.
Highlights
Overuse of fossil fuels has resulted in serious environmental problems, and global energy shortages have become an increasingly urgent issue
The results show that the BiVO4 photoanode prepared by the improved chemical bath deposition (CBD) method has one of the highest current densities reported for unmodified BiVO4 films
Based on Incident photon-to-charge conversion efficiency (IPCE) (%) = charge-separation efficiency (Psep) 9 charge-transport efficiency (Ptrans) 9 interfacial charge-transfer efficiency (Pinter) at the interfacial solid–liquid junction, the IPCE characteristics are consistent with the fact that the addition of NaCl leads to higher solar-light absorption and charge-separation efficiency, considering that Pinter is regarded for use of a co-catalyst
Summary
Overuse of fossil fuels has resulted in serious environmental problems, and global energy shortages have become an increasingly urgent issue. The photocatalytic activity of bare BiVO4 is still not ideal for practical applications because of its excessive charge recombination, poor charge transport, and slow oxidation kinetics To address these issues, several strategies have been developed to improve the photoelectrochemical activity of BiVO4, such as doping with foreign elements (e.g., Mo and W) [8,9,10], reduction to create oxygen vacancies [11,12,13], and coupling with co-catalysts (e.g., FeOOH and Co–Pi) [14,15,16] or other semiconductors to form stable heterojunction photoanodes [17,18,19,20,21,22]. The hydrothermal method is generally applied to prepare BiVO4 films with exposed (040) facets [30]. The results show that the BiVO4 photoanode prepared by the improved CBD method has one of the highest current densities reported for unmodified BiVO4 films
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