Nitrogen-rich zeolitic imidazolate frameworks (ZIFs) are ideal precursors for the synthesis of metal single atoms anchored on N-doped carbon. However, the microporous structures of conventional ZIFs lead to low mass transfer efficiency and low metal utilization of their derivatives. Here, we construct a composite of Co single atoms anchored on nitrogen-doped carbon with a three-dimensional ordered macroporous structure (Co-SA/3DOM-NC) by two-step pyrolysis of ordered macro/microporous ZnCo-ZIF. Co-SA/3DOM-NC shows high activity in the oxidative esterification of furfural, achieving a 99% yield of methyl 2-furoate under mild reaction conditions, which is significantly superior to the microporous and the Co-nanoparticle counterparts. The high activity of Co-SA/3DOM-NC should be attributed to the CoN₄ centers with high intrinsic activity and the ordered macroporous structure, promoting the mass transfer of reactants and accessibility of active sites.

The preparation of supported high-density metal nanoparticles (NPs) is of great importance to boost the performance in heterogeneous catalysis. Thermal transformation of metal-organic frameworks (MOFs) has been demonstrated as a promising route for the synthesis of supported metal NPs with high metal loadings, but it is challenge to achieve uniform metal dispersion. Here we report a strategy of “spatial isolation and dopant anchoring” to resist metal aggregation in the pyrolysis of MOFs through converting a bulk MOF into dual-heteroatom-containing flower-like MOF sheets (B/N-MOF-S). This approach can spatially isolate metal ions and increase the number of anchoring sites, thus efficiently building physical and/or chemical barriers to cooperatively prevent metal NPs from aggregation in the high-temperature transformation process. After thermolysis at 1,000 °C, the B/N-MOF-S affords B,N co-doped carbon-supported Co NPs (Co/BNC) with uniform dispersion and a high Co loading of 37.3 wt.%, while untreated bulk MOFs yield much larger sizes and uneven distribution of Co NPs. The as-obtained Co/BNC exhibits excellent electrocatalytic activities in both hydrogen evolution and hydrazine oxidation reactions, and only a voltage of 0.617 V at a high current density of 100 mA·cm⁻² is required when applied to a two-electrode overall hydrazine splitting electrolyzer.