3D Hydrangea Macrophylla-like Nickel–Vanadium Metal–Organic Frameworks Formed by Self-Assembly of Ultrathin 2D Nanosheets for Overall Water Splitting
Junjun Lv, Panpan Liu, Fei Yang, Liwen Xing, Danni Wang, Xiao Chen, Hongyi Gao, Xiubing Huang, Yunfeng Lu, Ge Wang
Abstract
The development of highly efficient and low-cost bifunctional noble metal-free electrocatalysts for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is an effective strategy for improving efficiency. Herein, novel three-dimensional (3D) bimetallic metal–organic frameworks containing Ni and V with adjustable stoichiometry were synthesized on nickel foam successfully. Notably, Ni2V-MOFs@NF only require rather low overpotentials of 244 and 89 mV for the OER and HER, respectively, and expedites overall water splitting with 1.55 V at 10 mA cm–2 with robust durability during the 80 h test. The high efficiency of the novel obtained electrocatalysts should be attributed to the particular morphological design of the two-dimensional (2D) ultrathin nanosheets self-assembling into a 3D nanoflower and the electronic structure regulation resulting from the synergetic interaction between nickel and vanadium. Subsequent theoretical calculations reveal the following conclusions: (I) the exceptional electronic conductivity of Ni2V-MOFs shows enhanced optimization as a result of electronic structure reconstruction, (II) the energy barrier reduction of the rate-limiting step is responsible for the enhanced dynamics of Ni2V-MOFs for the OER, and (III) the facilitation of the adsorption of H+ and H2O plays a key role in progressing the HER catalytic activity of Ni2V-MOFs.