Effect of the Preferential Expose of Cobalt (111) Facet and its Collaborative Crystal Facet on the Hydrogenation of 4-Nitrophenol

Abstract

Cobalt-based composites have demonstrated promising catalytic potential for organic pollutant degradation. However, the influence of exposed basal facets on their catalytic activity remains insufficiently explored. In this study, Co@CN, Cu/Co@CN, and Zn/Co@CN composites with preferentially exposed Co(111), Cu(111)/Co(111), and Co(111)/Zn(002) facets, respectively, were synthesized via a facile hydrothermal method. The facet-dependent catalytic performance and reaction mechanisms were systematically investigated through the reduction of 4-nitrophenol (4-NP). Experimental results combined with density functional theory (DFT) calculations revealed that the Co(111) facet was identified as a critical determinant of both catalytic activity and reaction pathways. Furthermore, we also tried to reveal how the preferential growth of co-exposed facets (Cu(111)/Co(111) and Co(111)Zn(002)) modulate catalytic activity and reaction pathways. As a results, the Cu/Co@CN with preferential exposed facet Cu(111)/Co(111) achieved increasing efficiency in reducing 4-NP to 4-aminophenol (4-AP) within 90s, with a pseudo-first-order rate constant (k) of 0.720 min^-1. Revealing that the synergy between Cu(111) and Co(111) exemplifies how crystal facets synergistically influenced to catalytic activity and reaction process. Moreover, the catalysts also showed durability over six cycles. The outcomes of this study provide new insights into comprehensiveness exposed crystal plane dependent activity and the design of efficient transition-metal catalysts using the facet strategy for effective degradation of certain pollutants in wastewater.

Graphical Abstract