Spin Density Modulation by Ru Nanoparticles in ZIF-67 Framework for Magnetically Enhanced Water Splitting Reaction
Swayamprakash Biswal1, Biswajit Mishra1, Bijay P Tripathi1
1Department of Materials Science and Engineering, Indian Institute of Technology Delhi, New Delhi, India.
None:
Introducing magnetic interactions into electrocatalyst development enables modulation of spin states and provides a pathway to accelerate water-splitting kinetics. In this study, a RuNP/ZIF-67 nanocatalyst is synthesized by immobilizing ruthenium nanoparticles onto the zeolitic imidazolate framework-67 (ZIF-67), which facilitates interfacial charge transfer and significantly alters the cobalt divalent to trivalent cation ratio compared to pristine ZIF-67. Such modulation in oxidation states modifies the electronic configuration of cobalt centers to enhance spin-spin coupling and induce ferromagnetism in the electrocatalyst. Stabilization of Ru nanoparticles enables synergistic tuning of the electronic and magnetic properties, directly contributing to enhanced catalytic activity. Under a 240 mT magnetic field, RuNP/ZIF-67 reduces the hydrogen evolution reaction (HER) overpotential from 68 to 51 mV and the oxygen evolution reaction (OER) overpotential from 210 to 182 mV, resulting in a decrease in overall cell voltage from 1.56 to 1.53 V. Control experiments using a rotating disk electrode (RDE) distinguish the spin-polarized contribution, while long-term chronopotentiometry and pulse-chronoamperometry confirm stable magneto-electrochemical performance. In situ operando studies provide mechanistic insights into the reaction pathway, supporting the observed catalytic performance and stability of RuNP/ZIF-67. Together, these findings establish RuNP/ZIF-67 as a robust bifunctional electrocatalyst for magnetically enhanced water splitting.
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