Showing papers by "Yingpu Bi published in 2020"

Tuning surface electronegativity of BiVO4 photoanodes toward high-performance water splitting

Abstract: Photoelectrochemical (PEC) water splitting is a promising technique for converting solar energy into hydrogen fuels, while its practical applications are mainly restricted by the relatively low photo-conversion efficiencies. Herein, we demonstrated a simple surface fluorination process for drastically promoting the PEC water oxidation activity of BiVO4 photoanodes, achieving a remarkable photocurrent density of 3.2 mA cm−2 at 1.23 V vs. reversible hydrogen electrode (RHE) under AM 1.5 G illumination, one of the highest values of BiVO4 electrodes without cocatalysts. After in-situ formation of CoF2 cocatalysts, the photocurrent density could be further increased up to 5.1 mA cm−2 (1.23 VRHE), accompanying by a remarkably negative shift of onset-potential (270 mV). Systematic studies clearly reveal that tuning surface electronegativity of BiVO4 photoanodes could drastically promote the charge separation efficiencies of both surface and bulk up to nearly 100%. This work may provide a facile but effective approach for constructing the highly efficient BiVO4 photoanodes for solar water splitting.

Dual-bonding interactions between MnO2 cocatalyst and TiO2 photoanodes for efficient solar water splitting

Abstract: Severe charge recombination and sluggish water oxidation kinetics greatly limited the practical applications of photoelectrochemical (PEC) water splitting. Herein, we demonstrated the nitrogen plasma treatment for simultaneously achieving oxygen vacancies and N-doping on TiO2 nanotube arrays. More importantly, the oxygen vacancies and N-doping could effectively promote the selective construction of MnO2 cocatalyst anchored with Mn-O/N bonds on TiO2 nanotube arrays, which could efficiently narrow charge depletion layer and promote the holes transfer from TiO2 to MnO2. As expected, this photoanode achieves a remarkably increased PEC performance (1.95 mA cm−2 at 1.23 VRHE), up to 3.4 times higher than that of pristine TiO2 (0.57 mA cm−2 at 1.23 VRHE), and excellent stability for water splitting. These demonstrations may provide a new insight for designing highly efficient TiO2-based photoanodes for solar energy conversion.

Homostructural Ta3N5 nanotube/nanoparticle photoanodes for highly efficient solar-driven water splitting

Abstract: Herein, we demonstrated a one-step ammonia treatment for fabricating homostructural Ta3N5 nanotube/nanoparticle photoanodes with a top-open structure. Compared with the relatively low activities of traditional Ta3N5 nanotube photoanode, this homo-photoanode exhibited a remarkably enhanced photocurrent density (1.58 mA cm−2 at 1.23 V vs. reversible hydrogen electrode (RHE)). Moreover, after the decoration of Co(OH)x cocatalyst, the photocurrent density could be further increased up to 8.73 mA cm−2 at 1.23 VRHE, accompanying with the significantly improved water oxidation stability as well as an evident negative shift of onset-potential (200 mV). More detailed studies reveal that the significantly promoted PEC activities should be attributed to the matched bandgaps between Ta3N5 nanotube and nanoparticle as well as the ordered top-open nanoarchitecture, which could accelerate charge separation and provide more active sites for water oxidation. Thereby, the construction of homostructural semiconductor photoanodes should be highly promising for promoting the development of PEC water splitting for practical applications.