Improved Photocurrents for Water Oxidation by Using Metal–Organic Framework Derived Hybrid Porous Co3O4@Carbon/BiVO4 as a Photoanode

Graphical Don’t look beyond the surface! A highly porous Co 3 O 4 @carbon/BiVO 4 photoanode is obtained by a facile metal–organic framework templated synthesis route. This photoanode can effectively suppress interfacial electron–hole recombination for water oxidation (see figure). Efforts to improve the overall efficiency of photoelectrochemical water splitting by promoting interfacial charge transfer and suppressing electron–hole recombination remain a challenge. Highly porous Co 3 O 4 @carbon derived from metal–organic frameworks was successfully embedded on the surface of BiVO 4 nanosheets. The Co 3 O 4 @carbon/BiVO 4 composites were fully characterised by a variety of techniques, including powder XRD, diffuse reflectance UV/Vis spectroscopy, BET surface area calculations, SEM, TEM, energy-dispersive X-ray spectroscopy, high-angle annular dark-field scanning TEM, and X-ray photoelectron spectroscopy. The construction of a heterojunction between porous Co 3 O 4 (p-Co 3 O 4 ) and BiVO 4 significantly promoted charge transfer and suppressed the recombination of holes and electrons. Consequently, the p-Co 3 O 4 @carbon/BiVO 4 photoanode demonstrated approximately tenfold higher photocurrent density relative to bare BiVO 4 and bulk Co 3 O 4 /BiVO 4 for water oxidation under the same conditions. Also, this system displayed good durability for water oxidation and could be recycled at least three times without any loss of catalytic activity.