Ternary WO 3 /Porous‐BiVO 4 /FeOOH Hierarchical Architectures: Towards Highly Efficient Photoelectrochemical Performance

Developing photoanodes showing both a high solar harvesting efficiency and efficient charge separation/transfer is recognized as one of the key challenges for water splitting. In the presented work, we report a strongly coupled ternary WO 3 /porous‐BiVO 4 /FeOOH hierarchical architecture as photoanode for high PEC performance,which was constructed by unique foaming‐assisted electro‐spraying of porous BiVO 4 frameworks and photodeposition of a FeOOH layer, respectively. As a proof of concept, the as‐fabricated WO 3 /porous‐BiVO 4 /FeOOH photoanode yielded a photocurrent density of ∼4.4 mA cm −2 at 1.23 V vs. RHE, ∼4 and 10 times higher than that of the BiVO 4 and WO 3 counterparts, respectively. Because of the surface passivation of FeOOH, the onset potential could be substantially reduced to ∼200 mV in the presence of sacrificial agent under AM 1.5G (100 mW cm −2 ) simulated sunlight illumination, which was lowered by ∼100 mV in comparison to those of BiVO 4 and WO 3 analogues. The mechanism for the enhanced PEC activities of ternary WO 3 /porous‐BiVO 4 /FeOOH hierarchical architectures was proposed.