Atomically Dispersed Single- and Dual-Boron-Atom Nanocatalysts for Electrochemical N2 Reduction to Ammonia: Mechanistic Insights from First-Principles Studies and Synthetic Challenges

Abstract

The electrochemical nitrogen reduction reaction (eNRR) has emerged as a promising alternative to the energy-intensive Haber–Bosch process for sustainable ammonia production under ambient conditions. However, the activation of the inert N≡N bond and the suppression of the competing hydrogen evolution reaction (HER) remain major challenges. In this context, atomically dispersed boron-based nanocatalysts, comprising isolated boron sites and boron-containing dual-atom motifs anchored on nanostructured supports, have emerged as promising metal-free platforms for electrochemical N2 reduction to ammonia, wherein the electron-deficient boron centers enable efficient activation and fixation of dinitrogen. At the nanoscale, the catalytic behavior of these systems is governed by the local coordination environment, subnanometer confinement, defect chemistry, and interfacial electronic coupling between boron centers and the host support. Owing to their electron-deficient p-orbital configuration, isolated boron centers exhibit strong Lewis acidity and unique σ-donation/π-back-donation interactions with N2, enabling effective bond polarization and activation without reliance on d-orbital chemistry. This review provides a comprehensive overview of single-boron atom catalysts (SBACs), homonuclear double- and multiboron atom catalysts, and boron-based heteronuclear dual-atom catalysts (BHDACs), investigated through first-principles simulations. We critically analyze mechanistic pathways (distal, alternating, enzymatic), charge transfer characteristics, electronic structure descriptors, scaling relationships, and limiting potentials reported for atomically dispersed boron-based catalysts across diverse two-dimensional nanomaterials, including graphene, graphitic carbon nitride, MXenes, and graphdiyne. Particular emphasis is placed on the cooperative electron-reservoir behavior of adjacent boron atoms, the modulation of adsorption thermodynamics via coordination engineering, and emerging machine-learning-assisted catalyst screening strategies. Furthermore, key synthetic challenges such as stabilizing isolated boron centers, controlling coordination environments, preventing aggregation, and achieving unambiguous structural characterization are discussed. Finally, we outline future directions integrating constant-potential simulations, microkinetic modeling, and operando spectroscopic validation to bridge the gap between theoretical predictions and experimentally viable boron-based eNRR nanocatalysts. This review aims to establish mechanistic design principles and provide a roadmap for the rational development of next-generation boron-centered nanocatalysts for sustainable ammonia synthesis.