Enhanced Hydrogen Precipitation Activity Of Gd@MoS₂ Single-atom Catalysts By Magnetic Heating Effect

With the continuous development of society,the increasingly serious energy crisis and environmental problems have become one of the most urgent problems of the century.Hydrogen energy is widely studied as the ideal clean energy source.However,hydrogen production from electrolytic water has relatively low efficiency and large energy consumption.Therefore,the preparation of a high-performance hydrogen precipitation catalyst has become a key factor to solve the problem.Single atom catalysts（SACs）have become a new frontier in the field of heterogeneous catalysis due to their high atomic utilization and high catalytic activity in electrocatalytic reactions.In recent years,significant efforts have been made to develop new synthesis strategies to further accelerate the catalytic process of single atom catalysts,mainly focusing on how to increase the loading density of single atom catalysts.However,with the increase of the loading density of single atoms,the higher surface free energy may lead to the inevitable aggregation of single atoms.In contrast to the pursuit of excellent catalytic performance in the design and synthesis of SACs,it is a promising way to improve the catalytic activity of SACs by using the external field modulation strategy.In recent years,theoretical and experimental studies have shown that the application of high frequency alternating magnetic field（AMF）and magnetic heating effect can improve the catalytic activity of magnetic catalysts.If AMF technique can trigger precise atomic-level magnetic heating effect on SACs,it will be a feasible and effective technique to improve the electrochemical activity of single atom catalysts.In this work,on the basis of large area synthesis of air stabilized monomolecular layer molybdenum disulfide（MoS₂）,electron paramagnetic resonance（EPR）technology confirms that MoS₂ prepared by us has a large number of sulfur vacancies.Then,pulse laser molecular beam epitaxy（L-MBE）technology is used to anchor Gd atoms in the sulfur vacancy of MoS₂.Due to the strong hybridization between Gd（4f）,Mo（4d）and S（3p）,the ferromagnetic behavior of MoS₂ at room temperature is finally realized.Moreover,spin flip experiments have confirmed that the active site Gd in the Gd@MoS₂ single atom catalyst prepared by us has a spin flip（or canting）phenomenon,and the external alternating magnetic field is used to make the spin flip（or canting）of Gd single atom,thus precisely triggering the magnetic heating effect at the atomic level.The current density of Gd@MoS₂ single atom catalyst with alternating magnetic field is nearly 9.5 times higher than that without alternating magnetic field.This magnetic heating effect limited near the active site plays a key role in breaking the limit of hydrogen evolution activity of single atom catalysts.