Magnetic field-enhanced photoelectrochemical water splitting of Co₃O₄/TiO₂ for efficient oxygen evolution

Effective separation of photogenerated carriers plays a vital role in governing the efficiency of photo-electrocatalytic reactions. However, the advancement in enhancing the intrinsic carrier separation efficiency of semiconductors has shown limited progress. Herein, we reported the use of a magnetic field to improve the photoelectrochemical water splitting of a magnetic Co₃O₄/TiO₂ photoanode by boosting the photogenerated carrier separation efficiency. In the presence of the magnetic field, oxygen evolution reaction occurs with a high photocurrent density of 0.86 mA cm⁻² at 1.23 V versus V_RHE, and an applied bias photon-to-current efficiency of 0.342% at 0.61 V_RHE. Moreover, the photoanode maintains its oxygen evolution reaction for more than 400 h with photocurrent decays by ca. 10%. Observations made in this effort show that the enhancement of photo-electrocatalytic efficiency by a magnetic field is a consequence of the effect of the Lorentz force generated by the magnetic field on photogenerated carriers and ions near the Co₃O₄/TiO₂ photoanode, which improves the carrier separation efficiency and the bubble release rate. The results suggest that manipulating photoelectrode carriers by using a magnetic field is a promising strategy to design high-performance photoelectrochemical for water splitting.