Effective Charge Carrier Utilization of BiVO₄ for Solar Overall Water Splitting

Abstract

Solar energy-driven overall water splitting (OWS) is an attractive way for generating clean and renewable green hydrogen. One key challenge is the construction of OWS systems with high solar energy conversion efficiencies, in which how to manipulate photoexcited charge carriers to efficiently participate in the reaction is the top priority. In recent years, bismuth vanadate (BiVO 4 ) has emerged as one of the most promising materials for photo(electro)catalytic OWS and considerable progress has been achieved. In this review, recent advances of BiVO 4 -constituted OWS systems in both photoelectrocatalytic and photocatalytic approaches are presented in a mainline of effective charge carrier utilization. Various strategies for improved charge carrier utilization, including band structure engineering, improving charge separation, reducing charge recombination, and accelerating reaction kinetics, are summarized and analyzed in detail. Finally, perspective and outlook on further exploring the application potential of BiVO 4 are proposed.

Biofuels and hydrogen production: back to the Langmuir–Blodgett approach for large-scale structuration of Bi-based photoelectrodes

“…To quote a few: a rigorous characterization dataset with evidence of negligible impurities impeding the excellent process of photocatalysis, a comparison of catalysts in terms of quantum yield (QY) instead of turnover frequency (TOF), or reporting both the catalyst activity in terms of mass and surface area per unit. Among the reviews and studies encountered in the specific case of BiVO 4 , 15–21 we observed an excellent characterization procedure with deep scrutiny of the catalyst surface. The latter reveals the encouraging performance of the BiVO 4 particles (scheelite) designed for a given photoelectrode, with a systematic photocurrent density between 3 and 6 mA cm −2 , low resistance (below 10 Ω), and high purity of the designed material.…”

“…Recent advancements in the development of photoelectrocatalysts have focused on transition metal oxides, 13,14 particularly scheelite-type monoclinic BiVO 4 , sometimes completed by carbon moieties as cocatalysts (GO, MWCNT), owing to their advantages in scaling up photoelectrodes, such as an adapted band gap for solar absorption (2.4 eV (VIS)), efficient charge separation, and atomic element availability. [15][16][17][18][19][20][21] Although these compounds are still under study, ongoing research aims to validate their efficiency and long-term stability under real working conditions.…”

Surface Hydroxylation during Water Splitting Promotes the Photoactivity of BiVO4(010) Surface by Suppressing Polaron-Mediated Charge Recombination

“…Solar water splitting with the assistance of photocatalysts, i.e., direct conversion of solar energy into hydrogen energy, − provides a promising route to solve the energy crisis. Bismuth vanadate (BiVO 4 ) has emerged as one of the most promising visible-light photoanode materials in recent years, due to an ideal bandgap (∼2.4 eV), a relatively high conduction band edge (0.02 V vs RHE), and a low bias voltage to achieve the reduction potential of water. − However, the performance of BiVO 4 photocathodes is limited by low charge carrier mobility (∼0.04 cm 2 V –1 s –1 ) and rapid recombination of photogenerated electrons and holes, which make its actual catalytic efficiency lower than the theoretical value. − Due primarily to the photoexcitation-induced small polarons (hereinafter referred to as polaron) in BiVO 4 , − charge trapped by a deformed lattice limited charge transport, is insensitive to thermal activation under a certain temperature. , Furthermore, polarons created by oxygen vacancy can act as efficient recombination centers to quickly capture photogenerated electrons or holes and accelerate nonradiative charge recombination …”