Multichannel Charge Transport of a BiVO₄/(RGO/WO₃)/W₁₈O₄₉ Three-Storey Anode for Greatly Enhanced Photoelectrochemical Efficiency

Abstract

Photoelectrochemical (PEC) solar conversion is a green strategy for addressing the energy crisis. In this study, a three-storey nanostructure BiVO/(RGO/WO)/WO was fabricated as a PEC photoanode and demonstrated a highly enhanced PEC efficiency. The top and middle storeys are a reduced graphene oxide (RGO) layer and WO nanorods (NRs) decorated with BiVO nanoparticles (NPs), respectively. The bottom storey is the WO film grown on a pure W substrate. In this novel design, experiments and modeling together demonstrated that the RGO layer and WO NRs with a fast carrier mobility can serve as multichannel pathways, sharing and facilitating electron transport from the BiVO NPs to the WO film. The high conductivity of WO can further enhance the charge transfer and retard electron-hole recombination, leading to a highly improved PEC efficiency of the BiVO/WO heterojunction. As a result, the as-fabricated three-storey photoanode covered with FeOOH/NiOOH achieves an attractive PEC photocurrent density of 4.66 mA/cm at 1.5 V versus Ag/AgCl, which illustrates the promising potential of the three-storey hetero-nanostructure in future photoconversion applications.

Ni(OH)2‐WP Hybrid Nanorod Arrays for Highly Efficient and Durable Hydrogen Evolution Reactions in Alkaline Media

“…C dl was derived using the equation Dj = v C dl ,i nw hich C dl is the slope obtained by fitting the plot of Dj as af unction of v,w here v is the scan rate, using linear regression.A ss hown in Figure6c, the calculated C dl values for WP/CP and Ni(OH) 2 -WP/CP were 37.1 and 28.0 mF cm 2 ,r espectively.T he decreased electrochemical surface area of Ni(OH) 2 -WP/CP compared with that of WP/CP was attributed to the deposition of Ni(OH) 2 , which hindered the exposure of the WP surface to the electrolyte. [42,43] The fitting values of each component in the equivalent circuit are provided in Ta ble S2. The complex-plane impedance plots of Ni(OH) 2 -WP/CP,W P/CP and Ni(OH) 2 /CP obtained by electrochemicali mpedances pectroscopy (EIS) are shown in Figure 6d.E IS revealed the interfacial properties of the electrodes.…”

“…To investigate the influence of Ni(OH) 2 deposition on the active surfacea rea of WP/CP catalysts, we tested the doublelayer capacitance (C dl )o fN i(OH) 2 -WP/CP and WP/CP,w hich represents the electrochemical surface area.F igure 6a and bd em- Figure S13. [42,43] The fitting values of each component in the equivalent circuit are provided in Ta ble S2. The radius of the semicirclef or Ni(OH) 2 -WP/CP was clearly smaller compared with that for WP/CPa nd significantly smaller than that for Ni(OH) 2 /CP,i ndicating that R ct of Ni(OH) 2 -WP/CP was smaller than those of WP/CP and Ni(OH) 2 /CP.T his result revealed the rapid reaction rate of the hybrid catalysti na lkaline HER kinetics, in good agreement with the Ta fel slope of Ni(OH) 2 -WP/CP,w hich was the lowest among the Ni(OH) 2 -WP/ CP,W P/CP and Ni(OH) 2 /CP catalysts.…”

Insight into the PEC and interfacial charge transfer kinetics at the Mo doped BiVO4photoanodes

“…[15][16][17][18] However, the slow surface catalytic activity, short hole diffusion length, fast electron-hole recombination are major challenges with the BiVO 4 . 6,[19][20][21][22] To overcome these challenges, a number of the strategies have been widely investigated such as; nanostructure control, [23][24][25][26] band engineering, 17,[27][28][29][30][31][32][33][34] heteroatom doping, [35][36][37][38][39][40][41] generation of oxygen vacancy 22,[42][43][44] and the oxygen evolution catalyst (OEC) incorporation. 18,[45][46][47][48][49][50][51][52][53] SnO 2 has been used for the heterojunction formation in the BiVO 4 system which suppresses the back electron-hole recombination process.…”

Ultrasmall Ag Clusters Modified W18O49 Ultrathin Nanowires for Sensitive Surface Enhanced Raman Spectroscopy Detection

“…In the details, the highest occupied molecule orbital (HOMO) and lowest unoccupied molecule orbital (LOMO) of R6G are at −5.7 and −3.4 eV, respectively. For W 18 O 49 , its conduction band (CB) and valence band (VB) are at −5.1 and −7.7 eV, respectively . The defectstate level induced by oxygen vacancies is reported at −6.6 eV.…”