Single-atom catalysts are becoming a hot research topic owing to their unique characteristics of maximum specific activity and atomic utilization. Herein, atomically dispersed Co on a N-doped carbon matrix with an enzyme-like M–N x structure has been developed as a bifunctional biosensor to detect hydrogen peroxide (H2O2) and dopamine (DA). It features 100% atomic utilization, high electrochemical activity and selectivity, and strong stability in various pH environments. The abundance of Co-N x sites can be increased via regulating calcination temperature, and as a result, the sensing performance is significantly improved. This platform could selectively catalyze the oxidation of DA and the reduction of H2O2 at different holding potentials. The optimal Co-N-C-800 affords high sensitivity (H2O2: 943.9 μA mM–1 cm–2 and DA: 979.6 μA mM–1 cm–2), low detection limit (H2O2: 0.13 μM and DA: 0.04 μM), high selectivity, and robust stability. At the same time, H2O2 and DA released by PC12 can be detected, which proved the feasibility of the enzyme-like single-atomic materials in electrochemical biosensing.

As a promising route to hydrogenate organic compounds at ambient conditions, electrocatalytic hydrogenation (ECH) urgently demands noble-metal-free electrocatalysts with satisfactory activity and selectivity. Here, molybdenum disulfide intercalated by dimethylamine (MoS2-DMA) demonstrates its superiority associated with the engineered interlayer chemistry in the ECH of nitroarenes to anilines. The in situ intercalation by DMA cations leads to the phase transition from semiconducting 2H to metallic 1T and the formation of abundant sulfur vacancies, which is beneficial for activating nitro groups and stabilizing chemisorbed H intermediate toward fast hydrogenation. In a wide potential range of −0.08 to −0.48 V (vs reversible hydrogen electrode (RHE)), MoS2-DMA affords the excellent ECH performance of p-nitrostyrene to p-aminostyrene with high Faradic efficiency (>90%), yield (>90%), and selectivity (>99%), outperforming typical MoS2. The good efficiency of such intercalated MoS2 within a broad substrate scope further verifies the promise of interlayer engineering for exploiting cost-efficient catalysts in an electrochemical refinery.

Crystal defects are pivotal to boosting catalytic performance and an in‐depth understanding of the working mechanism of transition‐metal chalcogenides (TMDs), but their facile and controllable engineering are yet challenging. Herein, a new route is introduced to engineer defects on MoS2 via in situ intercalation during its hydrothermal preparation, accomplishing the efficient catalytic transfer hydrogenation (CTH) of nitroarenes. The combination of multiple structural characterizations demonstrates that the density of S defects can be tuned by the intercalation of ammonium and dimethylamine cations due to lattice strain/distortion and ligand substitution. As a proof of concept, the defect‐dependent catalytic performance is evidenced in the CTH of nitrobenzene with isopropanol, highlighting the significance of coordinatively unsaturated Mo sites in generating reactive chemisorbed H for subsequent hydrogenation. The good efficiency of defective MoS2 within a broad substrate scope further verifies the promise of the intercalation‐driven defect‐engineering strategy for designing TMDs‐based catalysts.

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