Oxygen evolution reaction (OER) is of great significance for hydrogen production and CO₂ reduction via electrolysis, which, however, demands the development of highly active, durable, and cost-effective electrocatalysts in order to stride into a renewable energy era. In this article, we designed a highly efficient and long-term durable OER by coupling B and P into an amorphous porous NiFe-based electrocatalyst (a-NiFePB). The research has been published on May 30th 2019 in the Small.

By density functional theory calculations, we found the PB codoping in the a-NiFePB delocalizes both Fe and Ni at Fermi energy level and enhances p–d hybridization. The formation of a-NiFePB phase was further characterized by XAFS technique carried out at  1W1B-XAFS station of BSRF. From the Ni and Fe K-edge XANES and EXAFS spectra of the a-NiFePB, we obtained the fitted bond length and coordination numbers data of Fe-P(B), Fe-Fe(Ni), Ni-P(B), and Ni-Fe(Ni) bonds.

Figure a) Ni and b) Fe K-edge XANES spectra of the activated NiFePB using standard Ni₂P, FeP, Fe₂O₃, Fe₃O₄, NiO as references. k3-weighted Fourier-transform c) Ni and d) Fe Kedge EXAFS spectra of the samples.

The harmonized electronic structure, amorphous metallic phase, and unique porous framework of the a-NiFePB consequently improve the OER activity. It exhibits an extraordinarily low overpotential of 197 mV for harvesting 10 mA cm^-2 OER current density and 233 mV for reaching 100 mA cm^-2 under chronopotentiometry condition, with the Tafel slope harmoniously conforming to 34 mV dec^-1.

The superb stability would be associated with the intact surface oxide layer formation on the integral bulk structure. Our DFT simulation of the NiFePB structure determines the formation enthalpy is one order of magnitude more negative than that of the NiFe alloy, and the binding energy of O atom on the NiFePB is obviously smaller than on the NiFe alloy. The a-NiFePB thus exhibits dramatically higher thermodynamic stability, oxidation resistivity, and electro-oxide stability. Impressive long-term stability is experimentally evidenced by only 104 mV of overpotential is added after 1400 h operation at 100 mA cm^-2.

This work designed a function-integrated electrocatalyst that strategically comprises of multitudinous merits that directs a way for heading up a promising energy conversion alternative.

Article：

Fei Hu, Haiyun Wang, Yan Zhang, Xiaocheng Shen, Guanghui Zhang, Yanbo Pan, Jeffrey T. Miller, Kun Wang, Shengli Zhu, Xianjin Yang, Chengming Wang, Xiaojun Wu*, Yujie Xiong*, Zhenmeng Peng*, Designing Highly Efficient and Long-Term Durable Electrocatalyst for Oxygen Evolution by Coupling B and P into Amorphous Porous NiFe-Based Material, Small 2019, 15(28). 1901020.