Nano Energy 2018, 44, 353–363

Aiping Wu, Ying Xie, Hui Ma, Chungui Tian*, Ying Gu, Haijing Yan, Xiaomeng Zhang, Guoyu Yang, Honggang Fu*. (Nano Energy 2018, 44, 353–363)

Hydrogen is an ideal clean energy carrier. Developing the efficient and low-cost electrocatalysts for overall water splitting is of the great importance for the production of H₂. The popular bi-functional catalysts usually shown good activity for one half reaction at expense of the activity for another half-reaction, thus given a moderate performance for overall water splitting. Here, we have reported on integrating the active OER (Ni₃N) and HER (NiMoN) components as Ni₃N-NiMoN heterostructures for the effective overall water splitting. The heterostructures were constructed by the controllable nitridation of the Ni-Mo-O precursor anchored on carbon cloth (CC) under NH₃ atmosphere. By tuning the preparation parameters, the strong coupling catalysts on CC with suitable ratio of Ni₃N and NiMoN, moderated crystalline degree and crystalline size can be obtained. Under optimized condition, the Ni₃N-NiMoN catalysts exhibited good catalytic activity for both OER and HER in alkaline electrolyte. The catalysts can achieve a current density of 10 mA cm^-2 at an overpotential of 31 mV for HER, being close to Pt catalyst. Also, it only requiring an overpotential of 277 mV to reach current density of 10 mA cm^-2 for OER. Moreover, the cell assembled by the identical Ni₃N-NiMoN as both the cathode and anode needs only a cell voltage of 1.54 V to achieve current density of 10 mA cm^-2. The excellent performance of Ni₃N-NiMoN can be ascribed to the presence of both active OER and HER components and the promoted action of one component on performance of other components. This work is indicative for constructing the efficient and robust overall water splitting catalyst by integrating the active HER and OER catalyst as the heterostructures.