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5f Covalency Synergistically Boosting Oxygen Evolution of UCoO4 Catalyst
X. Lin, Y.-C. Huang, Z. Hu*(胡志偉), L. Li, J. Zhou, Q. Zhao, H. Huang, J. Sun, C.-W. Pao(包志文), Y.-C. Chang(張又中), H.-J. Lin(林宏基), C.-T. Chen(陳建德), C.-L. Dong, J.-Q. Wang*(王建強), and L. Zhang*(張林娟)
Electronic structure modulation among multiple metal sites is key to the design of efficient catalysts. Most studies have focused on regulating 3d transition-metal active ions through other d-block metals, while few have utilized f-block metals. Herein, we report a new class of catalyst, namely, UCoO4 with alternative CoO6 and 5f-related UO6 octahedra, as a unique example of a 5f-covalent compound that exhibits enhanced electrocatalytic oxygen evolution reaction (OER) activity because of the presence of the U 5f–O 2p–Co 3d network. UCoO4 exhibits a low overpotential of 250 mV at 10 mA cm–2, surpassing other unitary cobalt-based catalysts ever reported. X-ray absorption spectroscopy revealed that the Co2+ ion in pristine UCoO4 was converted to high-valence Co3+/4+, while U6+ remained unchanged during the OER, indicating that only Co was the active site. Density functional theory calculations demonstrated that the OER activity of Co3+/4+ was synergistically enhanced by the covalent bonding of U6+-5f in the U 5f–O 2p–Co 3d network. This study opens new avenues for the realization of electronic structure manipulation via unique 5f involvement.