Directional electronic tuning of Ni nanoparticles by interfacial oxygen bridging of support for catalyzing alkaline...

Metallic nickel (Ni) is a promising candidate to substitute Pt-based catalysts for hydrogen oxidation reaction (HOR), but huge challenges still exist in precise modulation of the electronic structure to boost the electrocatalytic performances. Herein, we present the use of single-layer Ti₃C₂T_x MXene to deliberately tailor the electronic structure of Ni nanoparticles via interfacial oxygen bridges, which affords Ni/Ti₃C₂T_x electrocatalyst with exceptional performances for HOR in an alkaline medium. Remarkably, it shows a high kinetic current of 16.39 mA cm_disk^-2 at the overpotential of 50 mV for HOR [78 and 2.7 times higher than that of metallic Ni and Pt/C (20%), respectively], also with good durability and CO antipoisoning ability (1,000 ppm) that are not available for conventional Pt/C (20%) catalyst. The ultrahigh conductivity of single-layer Ti₃C₂T_x provides fast transmission of electrons for Ni nanoparticles, of which the uniform and small sizes endow them with high-density active sites. Further, the terminated -O/-OH functional groups on Ti₃C₂T_x directionally capture electrons from Ni nanoparticles via interfacial Ni-O bridges, leading to obvious electronic polarization. This could enhance the Nids-O2p interaction and weaken Nids-H1s interaction of Ni sites in Ni/Ti₃C₂T_xenabling a suitable H-/OH-binding energy and thus enhancing the HOR activity.