Shedding light on the effect of pore orientation on hydrogenation over carbon-supported single-atom catalysts

Rational control of pore orientation holds great potential to enhance mass transfer in carbon-supported single-atom catalysts (SACs), thereby increasing single-atom site utilization and catalytic performance; however, this strategy remains underexplored in catalytic hydrogenation reactions. In this paper, cobalt single-atom catalysts supported on oriented porous carbon (Co-SAC/OPC) and cobalt single-atom catalysts supported on non-oriented porous carbon (Co-SAC/NOPC) were synthesized using the hard-template method, and their performance in hydrogenation reactions was systematically investigated using 1-chloro-4-nitrobenzene (p-CNB) hydrogenation as a model reaction. Results from experiments (diffusion, substrate size-dependent conversion, and recycling) and finite-element analysis show that oriented pores facilitate p-CNB diffusion more effectively than non-oriented pores. This faster transfer enhances the accessibility and utilization of single-atom cobalt sites, resulting in significantly improved hydrogenation performance of Co-SAC/OPC. This work establishes a general strategy for enhancing the performance of carbon-supported single-atom catalysts in hydrogenation catalysis and related reactions.