Multi-field coupling of photothermal effects and magnetism for boosting the electrocatalytic hydrogen evolution reaction performance

Abstract

The utilization of external fields to enhance electrochemical catalytic reactions has emerged as a promising approach in recent times. In this study, a multi-field coupling strategy involving light, heat, and magnetism is proposed to promote the electrocatalytic hydrogen evolution reaction (HER). A ferromagnetic CoFe₂O₄ modified MoS₂ (CoFe₂O₄/MoS₂) with a distinct photothermal effect is employed as a model catalyst. When an external magnetic field and light field are synergistically integrated into the electrochemical system, there is a remarkable reduction of about 50% in the overpotential. Specifically, an overpotential of 64 mV is achieved at a current density of 10 mA cm⁻². To further investigate the magnetic sensitivity of the ferromagnetic catalyst, the catalyst substrates are replaced with Mo₂C and ZnCdS, and the results indicate that the ferromagnetic catalyst shows significant sensitivity to external magnetic fields. The performance improvement can be attributed to multiple factors. Firstly, the application of a magnetic field enhances electron spin polarization, which in turn facilitates electron transfer kinetics. Secondly, the magnetohydrodynamic (MHD) effect causes the charged particles to move in a spiral manner, which modulates the local environment at the catalyst–electrolyte interface by forming spiral flow H₂ bubbles. Moreover, infrared thermal imaging confirms that the application of a magnetic field intensifies the photothermal effect of CoFe₂O₄/MoS₂. The resulting phonon bottleneck effect suppresses phonon relaxation, providing additional thermal energy and consequently reducing the reaction barrier. This work proposes an innovative multi-field synergistic approach for constructing highly active non-precious metal electrocatalysts.