Achieving long-term stable BiVO4 photoanodes for solar water splitting via carbon-layer protecting combined with active centers dynamic repairing

Abstract

Although great interest is focused on highly active photoanodes for efficient photoelectrochemical (PEC) water splitting, the issue on improving stability during oxygen evolution reaction (OER) is seldom discussed by far. Herein, a simple chemical way to construct carbon functional interlayer between bismuth vanadate (BiVO4) and NiFe layered double hydroxide (NiFe-LDH) co-catalyst, combined with hydroxylation, can significantly improve the activity and stability. The enhanced electronic conductivity by carbon layer and formed strong polarization electronic field via surface hydroxylation, promote the interfacial charge transfer and bulk charge separation. More importantly, the carbon layer combined with more efficient redeposition of Fe active centers in NiFe-LDH catalysts caused by enhanced adsorption of Fe(III) onto Ni sites via hydroxylation, can greatly improve the OH-BiVO4@C@NiFe-LDH photoanode stability. With the synergistic effects of carbon functional interlayer and self-healing mechanism, OH-BiVO4@C@NiFe-LDH photoanode achieves extremely high photocurrent density (5.31 mA cm−2 at 1.23 versus the RHE), even maintaining more than 87.5 % of the initial photocurrent density within 20 h irradiation in KBi electrolyte with Fe(III) ions. This work provides a new strategy to enhance the performance of BiVO4–based photoanodes, especially for achieving long-term stability during OER.