BiVO4 Nanoparticle-Modified WO3 Nanosheet Arrays Via a Stepwise Spin-Coating Process for Improved Photoelectrochemical Performance

A photoelectrode of WO3 nanosheet@BiVO4 nanoparticle heterostructured arrays (WO3@BiVO4 HAs) on a transparent F-doped SnO2 glass substrate was designed and manufactured using a hydrothermal and subsequent stepwise spin-coating process. The size and the distribution of BiVO4 nanoparticles on the surface of WO3 NSs can be regulated by the number of the stepwise spin-coating cycles. SEM, UV-vis, TEM, and XPS were used to characterize the obtained samples. The PEC performance can be optimized by controlling the number of the stepwise spin-coating cycles. The results of the photoelectrochemical (PEC) measurements display that the WO3@BiVO4 HA photoelectrodes obtained at 8 cycles showed a higher photocurrent density (about 3.5 times higher than that of the bare WO3 nanosheet array (NSA) photoelectrodes), lower charge transfer resistance (from 4019 to 904 omega cm2), improved electron-hole pair life (from 1 to 50.36 ms), and higher monochromatic photon-to-electron conversion efficiency (from 9 to 38.8%). The remarkable enhancement of the PEC performance may be due to the enhanced light capture, the large contact area with the electrolyte, and the improvement of charge transfer and separation by synergizing the band structure, morphology of photoelectrode, and the reasonable modification of BiVO4 nanoparticles using a stepwise spin-coating process.