Cobalt Hexacyanoferrate on BiVO4 Photoanodes for Robust Water Splitting

• Published in: ACS applied materials & interfaces Vol. 9; no. 43; pp. 37671 - 37681
• Main Authors: Hegner, Franziska Simone, Herraiz-Cardona, Isaac, Cardenas-Morcoso, Drialys, López, Núria, Galán-Mascarós, José-Ramón, Gimenez, Sixto
• Format: Journal Article
• Language: English
• Published: American Chemical Society 01.11.2017
• Subjects: photoelectrocatalysis; Prussian blue; water splitting; electrochemistry; computational chemistry; oxygen evolution
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.7b09449

The efficient integration of photoactive and catalytic materials is key to promoting photoelectrochemical water splitting as a sustainable energy technology built on solar power. Here, we report highly stable water splitting photoanodes from BiVO4 photoactive cores decorated with CoFe Prussian blue-type electrocatalysts (CoFe-PB). This combination decreases the onset potential of BiVO4 by ∼0.8 V (down to 0.3 V vs reversible hydrogen electrode (RHE)) and increases the photovoltage by 0.45 V. The presence of the catalyst also leads to a remarkable 6-fold enhancement of the photocurrent at 1.23 V versus RHE, while keeping the light-harvesting ability of BiVO4. Structural and mechanistic studies indicate that CoFe-PB effectively acts as a true catalyst on BiVO4. This mechanism, stemming from the adequate alignment of the energy levels, as showed by density functional theory calculations, allows CoFe-PB to outperform all previous catalyst/BiVO4 junctions and, in addition, leads to noteworthy long-term stability. A bare 10–15% decrease in photocurrent was observed after more than 50 h of operation under light irradiation.