Transition Metal Functionalized CNS as High-Performance Trifunctional Catalysts with Integrated Descriptors toward Hydrogen Evolution, Oxygen Evolution, and Oxygen Reduction Reactions: A Case of High-Throughput First-Principles Screening within the Framework of TM-N@CNS.

In energy conversion and storage technologies, the design of highly efficient trifunctional electrocatalysts integrating with the high hydrogen evolution reaction (HER) and oxygen evolution/reduction reaction (OER/ORR) activities is highly desirable. Herein, utilizing first-principles computations, a novel periodically ordered macropore CNS monolayer was proposed, and the stability analysis attests to its good stability. Single transition metal (TM) atom anchored onto this newly proposed CNS monolayer to form single-atom catalysts, as achieved by TM-N@CNS, among which the Co-N@CNS is the most promising multifunctional catalyst toward HER/OER/ORR with low overpotential of 0.01/0.59/0.3 V; meanwhile, the Rh-N@CNS can be used as a bifunctional OER/ORR catalyst with low overpotential of 0.37/0.44 V, overmatching the landmark Pt (111) and IrO/RuO catalysts. Particularly, the TM-d orbital in TM@CNS is remarkably hybridized with the O-p orbital of oxygenated intermediates, so that the lone electrons initially located at the antibonding orbital pair up and fill the downward bonding orbital, allowing OH* to be suitably adsorbed on TM@CNS, enhancing the catalytic performance. The relevant attributes, such as good stabilities and metallic features, ensured their applications in ambient conditions. Moreover, multilevel descriptors were constructed to clarify the origin of activity on TM@CNS, such as Δ (Gibbs free energy of OH*), ε (d-band center), COHP (crystal orbital Hamilton population), / (number of d/d + s electrons) and φ (descriptor), among which the filling of outer d-electrons of TM atom significantly affects the value of Δ that can determine the overpotential and, thus, become a key descriptor.