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

Abstract

Directed modulation of the active centers in carbon-based catalysts represents an effective strategy for enhancing their catalytic activity but still presents significant challenges. Herein, 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–N_x) 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–N_x in the IRR favored the dissociation of I₃⁻ complexes, whereas the smaller hydrogen adsorption free energy of Mo/Ni–N_x accelerated the HER kinetics. Building on these insights, we oriented three bimetallic nitrogen single atom active sites into a zeolitic imidazolate framework-derived porous carbon (M/Ni–NDPC, where NDPC = N-doped porous carbon; M = Fe, Cu, and Mo). Notably, Fe/Ni–NDPC single atom catalyst 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.