Highly efficient, field-assisted water splitting enabled by a bifunctional Ni3Fe magnetized wood carbon

Abstract

Various strategies have been used to improve the performance of non-noble catalysts, such as alloying, doping, and fine structure modulations. Herein, we reported a magnetic field-enhanced, bifunctional Ni3Fe/wood carbon electrode (Ni3Fe-CW) for efficient overall water splitting. Wood with numerous porous channels allows high loading of metal ions via the hydrothermal method, while the following high-temperature calcination leads to well-dispersed and uniform Ni3Fe nanoparticles, which are both electrocatalytically and magnetically active. As a result, the Ni3Fe-CW shows low overpotentials of 237 mV and 76 mV at 10 mA cm−2 for both oxygen and hydrogen evolutions under magnetic field (300 mT by a permanent magnet). Density functional theory calculations demonstrate that the Ni3Fe exhibits strong spin polarization under magnetic field with accelerated electron transfer, leading to lower reaction energy barrier and enhanced catalytic activities. Importantly, the electrolytic cell constructed by the bifunctional Ni3Fe-CWs as both cathode and anode displays a low cell voltage of 1.54 V at 10 mA cm−2 with an appropriate stability over 50 h (with a passive magnet). Considering the ubiquitous application of magnetic Fe, Co, Ni in catalytic reactions and the passive-radiation role of magnet, our strategy is promising for many energy conversion technologies toward highly efficient catalysis.