Metallic Bi Nanocrystal‐Modified Defective BiVO₄ Photoanodes with Exposed (040) Facets for Photoelectrochemical Water Splitting

Abstract

Metallic Bi nanocrystal‐modified defective BiVO4 photoanodes with exposed (040) facets were synthesized though the NaBH4 solution reduction method. B−O bonding at the surface of BiVO4 photoanodes is destroyed, which results in the removal of O atoms and forms oxygen vacancies at the beginning stage of the reduction process, and then Bi3+ ions are reduced to nanometer‐scale metallic Bi that is dispersed uniformly over the surface. BiVO4 photoanodes with this special structure exhibits a high performance for photoelectrochemical water splitting, owing to the synergistic effect of oxygen vacancies and metallic Bi. The presence of oxygen vacancies could significantly increase the capture ability of photogenerated electrons and improve the adsorption properties of H2O molecules in the process of photoelectrochemistry. Metallic Bi nanocrystals on the surface of BiVO4 photoanodes are beneficial for the photo‐response range as well as the separation and consumption of photogenerated carriers, owing to the surface plasmon resonance effect of Bi. In addition, the formation and function mechanism of metallic Bi and oxygen vacancies is discussed in detail.

Hierarchical Ta-Doped TiO2 Nanorod Arrays with Improved Charge Separation for Photoelectrochemical Water Oxidation under FTO Side Illumination

“…As shown in Figure 7a, the relatively lower resistance of electron transport inside the electrode ( R CT1 ) for the materials using intermediate volume of Ta precursor, especially for Ta:TiO 2 -140, indicates the proper Ta doping concentration can accelerate the electron transfer during the reaction. In addition, the low electrode–electrolyte interface resistance ( R CT2 ) of Ta:TiO 2 -140 was due to the high contact area of abundant nanoparticles on the top surface, which can promote surface water oxidation [38]. The materials under FS illumination exhibited smaller semicircles than those under TS illumination, implying the trap-free states significantly facilitate the electron transportation inside the electrode, and thus boost the surface water oxidation [39].…”

Boosting Photoelectrochemical Performance of BiVO4 through Photoassisted Self-Reduction

“…1−3 However, the photocurrent of BiVO 4 is limited to well below its theoretical maximum value by the slow carrier mobility in the bulk. 4−7 Thus far, extensive efforts and time have been invested to promote the photogenerated charge separation and transfer of BiVO 4 , including facet engineering, 8−10 heterojunction engineering, 11−13 metal deposition, 14,15 modification with electrolytes, 16,17 and doping. 18−20 In particular, heteroelement doping can regulate the electronic structure and atomic arrangement of BiVO 4 .…”

“…Thus far, extensive efforts and time have been invested to promote the photogenerated charge separation and transfer of BiVO 4 , including facet engineering, − heterojunction engineering, − metal deposition, , modification with electrolytes, , and doping. − In particular, heteroelement doping can regulate the electronic structure and atomic arrangement of BiVO 4 . A typical example is that a gradient concentration of tungsten was introduced in the BiVO 4 film, which created a distributed homojunction.…”

Semimetal Bismuth‐Enhanced Light Adsorption and Interface Charge Transfer in Bi@BiVO4

“…However, its high cost and rare resource severely limit the wide application. The cheap and abundant semimetal bismuth could be a good substitution for noble metals, hence bismuth‐based Schottky junctions have been reported . For example, Chen et al .…”

“…The cheap and abundant semimetal bismuth could be a good substitution for noble metals, hence bismuth-based Schottky junctions have been reported. [23][24][25][26][27][28][29][30][31][32][33][34] For example, Chen et al [23] prepared Ag-decorated Bi 2 O 3 nanospheres, which shows a higher visible-light activity than Bi 2 O 3 .Jing et al [26] prepared Bi@BiVO 4 hollow particles, however, the particles were 1-3 μm large and severely agglomerated. Xu et al [30] prepared Bi@BiVO 4 @V 2 O 5 using hydrogen reduction at 450 °C, in which the operation is not safe and the yield is low.…”