Reduced monoclinic BiVO4 for improved photoelectrochemical oxidation of water under visible light

Abstract

A monoclinic BiVO 4 film was grown on a transparent conducting substrate for photoelectrochemical oxidation of water. A photocurrent up to 2.3 mA cm −2 under visible light (λ > 420 nm) was achieved after treating the sample simply by electrochemical reduction followed by NaBH 4 . The high photocurrent is believed to be due to the improved carrier separation and transportation as a result of increased donor density. † Electronic supplementary information (ESI) available: Detailed information for experiment and XPS spectra. See

Photocharged BiVO4 photoanodes for improved solar water splitting

“…Likewise, the photocharging technique leads to the diminishing of this reduction wave, as shown in Figure 6(b). The observed redox waves have previously been shown to correspond to the reduction and re-oxidation of vanadium V 4+ / V 5+ , which may be a bulk process 32 . The fact that photocurrent density is related to the intensity of the redox waves, and hence to the concentration of V 4+ and V 5+ species, suggests that photocharging leads to alteration of the V 4+ to V 5+ ratio.…”

Facile synthesis of V4+self-doped, [010] oriented BiVO4nanorods with highly efficient visible light-induced photocatalytic activity

“…5 and Fig. 23,52,53 More strikingly, the time that is required to entirely decompose RhB is reduced to as less as 9 min using HT-BVO-NRs under the same conditions even though its adsorption for RhB is weakened greatly (23% of RhB). For comparison, the degradation reactions in the presence of commercial Degussa P25 and without any photocatalyst are also conducted.…”

“…37 In other words, V 4+ species is distributed throughout the nanorod, as well as the oxygen vacancies. 23 The ratio of adsorbed O (O ads ) and lattice O (O latt ) on the surface of the BVO-NRs, which is calculated to be 66 : 34 using GL fitting methods, could be greatly decreased to 34 : 65 for HT-BVO-NRs. [38][39][40][41] Oxygen vacancies with positive charge on the surface tend to adsorb some negative charged species, such as OH À and O 2À whose binding energies are around 531.5 eV, as shown in Fig.…”

“…23 The ratio of adsorbed O (O ads ) and lattice O (O latt ) on the surface of the BVO-NRs, which is calculated to be 66 : 34 using GL fitting methods, could be greatly decreased to 34 : 65 for HT-BVO-NRs. 23 In order to further identify the presence of V 4+ ions in BVO-NRs and HT-BVO-NRs, EPR measurement was carried out at room temperature, as shown in Fig. The binding energies of Bi 4f 7/2 and Bi 4f 5/2 are B159.0 eV and B164.3 eV, respectively, which agree well with the values reported in previous studies, as shown in Fig.…”

“…21 Reduced BiVO 4 containing V 4+ species has been obtained in several different ways, such as electrochemical reduction, hydrotreating and hydrothermal reduction with reducing additives. 10,23 Hence, an excess of V 4+ is detrimental to the photocatalytic performance of m-BiVO 4 and desirable m-BiVO 4 with both excellent absorbability and photocatalytic property can be achieved by adjusting the content of V 4+ through a low temperature heat treatment. 10,23 Hence, an excess of V 4+ is detrimental to the photocatalytic performance of m-BiVO 4 and desirable m-BiVO 4 with both excellent absorbability and photocatalytic property can be achieved by adjusting the content of V 4+ through a low temperature heat treatment.…”