Theoretical guidance for targeted modulation of metal-nitrogen active sites on 3D porous carbon to optimize electrocatalytic performance in energy conversion applications

Directed modulation of the active centers in carbon-based catalysts represents an effective strategy for enhancing their catalytic activity, but still presents significant challenges. Here, we propose a directed doping approach guided by density functional theory (DFT) to engineer functionalized carbon-based catalysts for the synergistic optimization of the triiodide reduction reaction (IRR) and hydrogen evolution reaction (HER). Specifically, DFT showed that bimetallic nitrogen active sites (M/Ni-Nx) with zero band gap and higher electron density at the Fermi energy level were found to be beneficial for electron transport in catalytic reactions. Longer I1-I2 bond lengths using Fe/Ni-Nx in the IRR favored the dissociation of I3- complexes, whereas the smaller hydrogen adsorption free energy of Mo/Ni-Nx accelerated the HER kinetics. Building on these insights, we oriented three bimetallic nitrogen active sites into a zeolite imidazole framework-derived porous carbon (M/Ni-NDPC, NDPC = N-doped porous carbon, M = Fe, Cu, and Mo). Notably, Fe/Ni-NDPC exhibits exceptional catalytic performance in the IRR with a corresponding solar cell efficiency of 8.14%, while Mo/Ni-NDPC demonstrates remarkable HER electrocatalytic activity with a low overpotential of 117.8 mV, aligning with the DFT results. This study presents a theory-guided experimental approach for the design of functionalized carbon-based catalysts, providing guidance for the construction of high-performance catalysts for energy conversion applications.