Synergistically Coupled Ni/CeO x @C Electrocatalysts for the Hydrogen Evolution Reaction: Remarkable Performance to Pt/C at High Current Density

In 1.0 M KOH, Ni2Ce1@C/500 catalystsexhibited Pt-like hydrogen evolution reaction activity with a lowoverpotential of 26 mV at 10 mA cm(-2) current density,and its overpotential at a high current density is much better thanthe benchmark commercial Pt/C and has a stability of more than 300h at 300 mA cm(-2). Incredibly active electrocatalysts comprising earth-abundantmaterialsthat operate as effectively as noble metal catalysts are essentialfor the sustainable generation of hydrogen through water splitting.However, the vast majority of active catalysts are produced via complicatedsynthetic processes, making scale-up considerably tricky. In thiswork, a facile strategy is developed to synthesize superhydrophilicNi/CeO x nanoparticles (NPs) integratedinto porous carbon (Ni/CeO x @C) by a simpletwo-step synthesis strategy as efficient hydrogen evolution reaction(HER) electrocatalysts in 1.0 M KOH. Benefiting from the electrontransport induced by the heterogeneous interface between Ni and CeO x NPs and the superhydrophilic structure ofthe catalyst, the resultant Ni2Ce1@C/500 catalystsexhibit a low overpotential of 26 and 184 mV at a current densityof 10 and 300 mA cm(-2), respectively, for HER witha small Tafel slope of 62.03 mV dec(-1) and robustdurability over 300 h, and its overpotential at a high current densityis much better than the benchmark commercial Pt/C. Results revealedthat the electronic rearrangement between Ni and CeO x integrated into porous carbon could effectively regulate thelocal conductivity and charge density. In addition, the oxygen vacanciesand Ni/CeO x heterointerface promote wateradsorption and hydrogen intermediate dissociation into H-2 molecules, which ultimately accelerate the HER reaction kinetics.Notably, the electrochemical results demonstrate that structural optimizationby regulating synthesis temperature and metal concentration couldimprove the surface features contributing to high electrical conductivityand increase the number of electrochemically active sites on the Ni/CeO x @C heterointerface, high crystal purity,and better electrical conductivity, resulting in its exceptional electrocatalyticperformance toward the HER. These results indicated that the Ni/CeO x @C electrocatalyst has the potential forpractical water-splitting applications because of its controlled productionstrategy and outstanding Pt-like HER performance.