Solution-processed yolk-shell-shaped WO3/BiVO4 heterojunction photoelectrodes for efficient solar water splittingElectronic supplementary information (ESI) available. See DOI: 10.1039/c7ta08452h

• Main Authors: Jin, Bingjun, Jung, Eunji, Ma, Ming, Kim, Sungsoon, Zhang, Kan, Kim, Jin Il, Son, Yongkeun, Park, Jong Hyeok
• Format: Journal Article
• Language: English
• Published: 06.02.2018
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c7ta08452h

The WO 3 /BiVO 4 heterojunction is regarded as one of the most promising photoanode materials for photoelectrochemical (PEC) water splitting. To improve the solar water splitting efficiency, maximizing the solar light absorption efficiency in a photoelectrode is still a critical issue. Here, to achieve the aforementioned need, we designed and fabricated a WO 3 film consisting of yolk-shell structured nanoparticles via solution processing. A thin BiVO 4 layer with a smaller bandgap was coated onto the surface and inside the WO 3 shells, providing a rationally designed inner space between the particles and the shell for better electrolyte accessibility. The yolk-shell-shaped PEC photoanode not only induces efficient light absorption but also plays an important role in electron collection from BiVO 4 due to an enlarged contact area. The structure-PEC performance relationship was studied by combining ultraviolet-visible (UV-vis) absorption spectroscopy with a specular and diffuse reflectance technique, which illustrates that the yolk-shell morphology has a superior light absorption ability than conventional hollow or dense film structures. The pure yolk-shell (Y-WO 3 /BiVO 4 ) photoanode possessed a photocurrent density of 2.3 mA cm −2 and achieved a highest value of ∼5.0 mA cm −2 after adding a Fe-Ni co-catalyst at a bias of 1.23 V vs. RHE under AM 1.5 illumination (100 mW cm −2 ). A novel yolk-shell-shaped WO 3 /BiVO 4 heterojunction photoanode was fabricated which is beneficial for efficient solar light utilization.