Conformal BiVO₄-Layer/WO₃-Nanoplate-Array Heterojunction Photoanode Modified with Cobalt Phosphate Cocatalyst for Significantly Enhanced Photoelectrochemical Performances

Abstract

Constructing semiconductor heterojunctions via surface/interface engineering is an effective way to enhance the charge carrier separation/transport ability and thus the photoelectrochemical (PEC) properties of a photoelectrode. Herein, we report a conformal BiVO-layer/WO-nanoplate-array heterojunction photoanode modified with cobalt phosphate (Co-Pi) as oxygen evolution cocatalyst (OEC) for significant enhancement in PEC performances. The BiVO/WO nanocomposite is fabricated by coating a thin conformal BiVO layer on the surface of presynthesized WO nanoplate arrays (NPAs) via stepwise spin-coating, and the decoration of Co-Pi OEC is realized by photoassisted electrodeposition method. The optimized Co-Pi@BiVO/WO heterojunction photoanode shows a maximum photocurrent of 1.8 mA/cm at 1.23 V vs RHE in a phosphate buffer electrolyte under an AM1.5G solar simulator, which is 5 and 12 times higher than those of bare WO and BiVO photoanode, respectively. Measurements of UV-vis absorption spectra, electrochemical impedance spectra (EIS) and photoluminescence (PL) spectra reveal that the enhanced PEC performances can be attributed to the increased charge carrier separation/transport benefited from the type II nature of BiVO/WO heterojunction and the promoted water oxidation kinetics and photostability owing to the decoration of Co-Pi cocatalyst.

Rational Design of a Coupled Confronting Z‐Scheme System Toward Photocatalytic Refractory Pollutant Degradation and Water Splitting Reaction

“…Additionally, the atomic concentrations of the constituents are compiled in Table S2 (Supporting Information). It indicates that atomic percent of the elements (except O and Cd) obtained from TEM–EDS is relatively higher than that obtained from XPS, which means comparatively more information is reflected about the catalyst surface …”

Enhanced Photoelectrochemical Performance by Interface Engineering in Ternary g‐C3N4/TiO2/PbTiO3 Films

“…[ 27 ] Compared to that of pristine PTO sample, PL peak of CN 0.10 /PTO sample was weaker, revealing a type II junction (Figure S3b, Supporting Information) between PTO and CN in which the photogenerated electrons on the conduction band (CB) of PTO was transferred to that of CN, photogenerated holes on the valance band (VB) of CN was transferred to that of PTO. [ 28 ] This type II junction increases the separation efficiency of photogenerated charge carriers, leading to the better PEC performance. [ 29 ] After the insert of TO buffer layer, two interfaces between PTO and TO, TO and CN were constructed.…”

Stepping towards Solar Water Splitting: Recent Progress in Bismuth Vanadate Photoanodes

“…A lower E CB of WO 3 allows facile electron injection from the CB of BiVO 4 to that of WO 3 , promoting the charge separation. [44,46,48,93,100] Notably, from the aspect of nanostructure design, Zhou et al utilized Bi 2 WO 6 as the starting material to synthesize a hierarchical BiVO 4 nanoporous sphere array film (Figure 11a). Multiple solar light scattering in the sphere arrays and voids along with the large effective thickness of the BiVO 4 photoanode induce efficient light harvesting compared to the flat film.…”

“…The most frequently reported heterojunction is WO 3 /BiVO 4 . A lower E CB of WO 3 allows facile electron injection from the CB of BiVO 4 to that of WO 3 , promoting the charge separation . Notably, from the aspect of nanostructure design, Zhou et al .…”