Biomass-Derived Atomically Dispersed Cu Catalysts: Synergetic Roles of Cu–N _<i>x</i> Centers and Hierarchically Porous Carbon Structures in Hydrogenation Reduction of Nitroarenes

Biomass waste utilization to produce desirable carbon-based catalysts opens new horizons for achieving carbon neutrality. Nevertheless, efficient manipulation of carbon support morphology and electronic structures of active sites remains a great challenge. By selecting adhesive-contained fiberboard waste as a C/N source and low-cost copper nitrate as a Cu donor, a well-designed carbon catalyst loaded with Cu atomic centers was constructed via a ZnCl2-assisted calcination strategy. Without adscititious N sources, the adhesive contributes to N doping into the carbon framework, further serving as Cu anchoring sites. Meanwhile, ZnCl2 adoption introduces abundant hierarchical pores, significantly improving the available surface area to enhance N doping and Cu dispersion. The as-synthesized catalyst (Cu ACs/aFC) exhibits impressive merits, such as a high specific surface area (∼1222 m2 g–1), homogeneously dispersed Cu sites with robust Cu–Nx configurations and tunable electronic structures, favorable surface hydrophilicity, and excellent electron migration, making it a promising candidate for catalytic reduction of nitroarenes and azo dyes. Taking 4-nitrophenol (4-NP) conversion into a high-value-added chemical (4-aminophenol) as an example, an impressive catalytic performance with a high TOF of 100.26 h–1 (∼2.1-fold that of its counterpart of Cu nanoparticle catalyst), as well as excellent reusability and long-term stability of up to 200 h, is achieved. Particularly, an efficient hydrogenation reduction toward a series of 4-NP analogues and azo dyes is demonstrated, displaying a huge application potential. Through selecting diverse metal precursors, the proposed strategy could be generalized to construct various biochar-based catalysts for advanced hydrogenation reactions.