Ir0/graphdiyne atomic interface for selective epoxidation

The development of catalysts that can selectively and efficiently promote the alkene epoxidation at ambient temperatures and pressures is an important promising path to renewable synthesis of various chemical products. Here we report a new type of zerovalent atom catalysts comprised of zerovalent Ir atoms highly dispersed and anchored on graphdiyne (Ir⁰/GDY) wherein the Ir⁰ is stabilized by the incomplete charge transfer effect and the confined effect of GDY natural cavity. The Ir⁰/GDY can selectively and efficiently produce styrene oxides (SO) by electro-oxidizing styrene (ST) in aqueous solutions at ambient temperatures and pressures with high conversion efficiency of ∼100%, high SO selectivity of 85.5%, and high Faradaic efficiency (FE) of 55%. Experimental and density functional theory (DFT) calculation results show that the intrinsic activity and stability due to the incomplete charge transfer between Ir⁰ and GDY effectively promoted the electron exchange between the catalyst and reactant molecule, and realized the selective epoxidation of ST to SO. Studies of the reaction mechanism demonstrate that Ir⁰/GDY proceeds a distinctive pathway for highly selective and active alkene-to-epoxide conversion from the traditional processes. This work presents a new example of constructing zerovalent metal atoms within the GDY matrix toward selective electrocatalytic epoxidation.

Ag Single Atoms Anchored on CeO2 with Interfacial Oxygen Vacancies for Efficient CO2 Electroreduction

Ag single-atom catalysts (SACs) have great potential in selective electrocatalysis of the CO₂ reduction reaction (CO₂RR) to CO, while it is still a challenge to achieve high current density and high atom efficiency simultaneously. Here, we present a new and simple in situ adsorption-reduction method to prepare Ag SACs supported on CeO₂ (Ag₁/CeO₂). It is found that Ag single atoms are anchored on CeO₂ through strong metal-support interaction (SMSI), and each Ag atom is accompanied with three interfacial oxygen vacancies. This Ag₁/CeO₂ exhibits high performance in the electrocatalytic CO₂RR with a high CO faradaic efficiency (FE) of >95% under a wide potential range. The turnover frequency (TOF) value can reach 50,310 h^-1 at FE_CO = 99.5% in H-cells. Notably, Ag₁/CeO₂ achieves an industrial-grade current density of 403 mA cm^-2 with a high FE_CO of 97.2% in flow cells. Experimental results combined with density functional theory calculation revealed that this superior performance was mainly ascribed to the existence of interfacial oxygen vacancies, which lead to the formation of Ag-O-Ce³⁺ atomic interfaces, and activates the Ce³⁺-O structures as the synergistic active center of Ag, thus promoting CO₂ adsorption and activation and reducing the reaction potential barrier of *COOH-to-*CO.

Atomically Dispersed Cu Anchored on Nitrogen and Boron Codoped Carbon Nanosheets for Enhancing Catalytic Performance

Development of high-performance heterogeneous catalytic materials is important for the rapid upgrade of chemicals, which remains a challenge. Here, the benzene oxidation reaction was used to demonstrate the effectiveness of the atomic interface strategy to improve catalytic performance. The developed B,N-cocoordinated Cu single atoms anchored on carbon nanosheets (Cu₁/B-N) with the Cu-N₂B₁ atomic interface was prepared by the pyrolysis of a precoordinated Cu precursor. Benefiting from the unique atomic Cu-N₂B₁ interfacial structure, the designed Cu₁/B-N exhibited considerable activity in the oxidation of benzene, which was much higher than Cu₁/N-C, Cu NPs/N-C, and N-C catalysts. A theoretical study showed that the enhanced catalytic performance resulted from the optimized adsorption of intermediates, which originated from the manipulation of the electronic structure of Cu single atoms induced by B atom coordination in the Cu-N₂B₁ atomic interface. This study provides an innovative approach for the rational design of high-performance heterogeneous catalytic materials at the atomic level.

Engineering Isolated Mn-N2C2 Atomic Interface Sites for Efficient Bifunctional Oxygen Reduction and Evolution Reaction

Oxygen-involved electrochemical reactions are crucial for plenty of energy conversion techniques. Herein, we rationally designed a carbon-based Mn-N₂C₂ bifunctional electrocatalyst. It exhibits a half-wave potential of 0.915 V versus reversible hydrogen electrode for oxygen reduction reaction (ORR), and the overpotential is 350 mV at 10 mA cm^-2 during oxygen evolution reaction (OER) in alkaline condition. Furthermore, by means of operando X-ray absorption fine structure measurements, we reveal that the bond-length-extended Mn²⁺-N₂C₂ atomic interface sites act as active centers during the ORR process, while the bond-length-shortened high-valence Mn⁴⁺-N₂C₂ moieties serve as the catalytic sites for OER, which is consistent with the density functional theory results. The atomic and electronic synergistic effects for the isolated Mn sites and the carbon support play a critical role to promote the oxygen-involved catalytic performance, by regulating the reaction free energy of intermediate adsorption. Our results give an atomic interface strategy for nonprecious bifunctional single-atom electrocatalysts.