Liu Ruirui, Jia Chen, Guo Boxia, Huang Yuhong*, Han Li*, Wu Ruizhi, Meyer Quentin, Lu Haochen, Yang Mengmeng, Cheong Soshan, Bo Xin* and Zhao Chuan*, , ACS Sustain. Chem. Eng., 2026, DOI: https://doi.org/10.1021/acssuschemeng.6c08072

Single-atomcatalysts (SACs) are promising for the electrochemical carbon dioxide reduction reaction (CO₂RR) owing to their maximum metal utilization and well-defined active sites. However, the low density of active sites and inadequate mass transport limit their electrocatalytic performance. Here, we report a highly ordered hierarchical porous Ni SAC incorporating nanoconfined ionic liquids (ILs) for CO₂RR. The interconnected macropores and mesopores provide efficient transport pathways, while hydrophobic ILs nanoconfined within the microporous network enhance local CO₂ availability. The hybrid catalyst delivers nearly unity CO Faradaic efficiency and enhanced partial current densities up to 32 mA cm^-2, outperforming conventional Ni-N-C catalysts. Moreover, its ability to maintain high activity under diluted CO₂ conditions further supports enhanced local CO₂ availability enabled by the nanoconfined ILs. Operando spectroscopies suggest enhanced catalytic engagement of Ni sites and significantly enhanced mass transfer enabled by the hierarchical porous structure and nanoconfinement of ILs. Density functional theory calculations further reveal that the ILs modulate the electronic structure of Ni sites and lower the formation energy of the key intermediates. This synergistic integration of hierarchical porosity and local microenvironment engineering offers a viable pathway for advancing high-performance electrocatalysis.

Figure1. Synthesis and morphology of HOPS NiNC@ILs and the corresponding pore structure and dispersion

First Author: Liu Ruirui, PhD candidate, University of New South Wales

Correspondence Authors: Prof. Zhao Chuan, University of New South Wales; Prof. Han Li, Zhengzhou University; Prof. Huang Yuhong, Institute of Process Engineering, Chinese Academy of Sciences; A/Prof. Bo Xin, Shaanxi Normal University

Full Text Link: https://doi.org/10.1021/acssuschemeng.6c08072