Modulation of Charge Redistribution in Heterogeneous CoSe-NiSe Coupling with TiCT MXene for Hydrazine-Assisted Water Splitting.

Integrating abundant dual sites of hydrazine oxidation reaction (HzOR) and hydrogen evolution reaction (HER) into one catalyst is extremely urgent toward energy-saving H production. Herein, CoSe-NiSe heterostructure coupling with TiCT MXene (CoSe-NiSe/MXene) is fabricated on nickel foam (NF) to enhance the catalytic performance. The heterogeneous CoSe-NiSe and MXene coupling effect can change the coordination of Ni and Co, resulting in adjusted interfacial electronic field and enhanced electron transfer from NiSe to CoSe especially near MXene surface. Also, the appearance of MXene can anchor more active sites, thereby abundant nucleophilic CoSe and electrophilic NiSe are formed induced by the charge redistribution, which can tailor d-band center, moderate H adsorption free energy (∆G ) and facilitate adsorption/desorption for hydrazine intermediates, contributing to much enhanced HER and HzOR performance. For example, the low potentials of -160.8 and 116.1 mV at 400 mA cm are seen for HER and HzOR with long-term stability of 7 days. When assembled as overall hydrazine splitting (OHzS), a small cell voltage of 0.35 V to drive 100 mA cm is obtained. Such concept of integrating abundant nucleophilic and electrophilic dual sites and regulating their d-band centers can offer in-depth understandings to design efficient bifunctional HER and HzOR electrocatalysts.