Guilan Fan

Layered double hydroxides (LDHs) are promising for supercapacitors but suffer from poor conductivity, severe agglomeration, and structural instability. Compositing with conductive polypyrrole (PPy) is an effective strategy to address these issues; however, the intrinsically weak interfacial interactions often lead to unsatisfactory charge transfer and poor cycling durability. Herein, a candied haws-like CoNi-LDH@PPy composite with strong interfacial coupling is designed via an in-situ transformation strategy using polypyrrole-anchored ZIF-67, which delivers an outstanding specific capacitance of 1083.4 C g-1 at 1 A g-1. Assembled into an asymmetric supercapacitor with activated carbon serving as the negative electrode, the device delivers an energy density of 58.5 Wh kg-1 at a power density of 1620 W kg-1 and maintains 98.72% of its initial capacitance over 10,000 cycles. As revealed by experimental and theoretical calculations results, the introduction of hierarchical hollow structure from PPy reduces the K⁺ surface diffusion energy barrier on LDH surface, and the strong interfacial coupling between CoNi-LDH and PPy through M-N coordination bonds facilitates the efficient charge transfer and ions transportation. This work offers a novel strategy for interface engineering of high‐performance supercapacitor electrodes and paves the way for the practical application of conductive polymer/layered double hydroxide composite in energy storage.

The rational design of single‐atom catalysts with precise coordination environment and high separation efficiency of photogenerated carriers is critical yet challenging to achieve efficient photocatalytic nitrogen reduction. Herein, we design and construct a defective photocatalyst featuring Fe single atoms immobilized in hollow BiOBr microtube using a plasma‐assisted synthesis strategy, where the Bi‐based metal–organic framework is used as sacrificial template. The dual vacancies of oxygen (V _O ) and bromine (V _Br ) are created in the BiOBr microtube and induce the formation of coordinatively unsaturated FeO ₅ configuration, where four oxygen atoms are from [Bi ₂ O ₂ ] ²⁺ units and one oxygen atom is located in the V _Br . Specially, the hollow catalyst with dual defects and FeO ₅ moiety exhibits 1.4 and 2.2 times higher ammonia production activity than another two V _Br ‐featuring catalysts with coordinatively saturated FeO ₆ configuration and unsaturated FeO ₄ configuration, respectively. As revealed by experimental and theoretical calculation results, the optimized catalyst with the FeO ₅ configuration reduces the energy barrier of electron transfer from Fe 3d orbitals to antibonding orbitals of N ₂ molecules, which favors the formation of a key *NNH intermediate in the N ₂ fixation reaction and the resultant efficient ammonia production.

The rational design of single‐atom catalysts with precise coordination environment and high separation efficiency of photogenerated carriers is critical yet challenging to achieve efficient photocatalytic nitrogen reduction. Herein, we design and construct a defective photocatalyst featuring Fe single atoms immobilized in hollow BiOBr microtube using a plasma‐assisted synthesis strategy, where the Bi‐based metal–organic framework is used as sacrificial template. The dual vacancies of oxygen (V _O ) and bromine (V _Br ) are created in the BiOBr microtube and induce the formation of coordinatively unsaturated FeO ₅ configuration, where four oxygen atoms are from [Bi ₂ O ₂ ] ²⁺ units and one oxygen atom is located in the V _Br . Specially, the hollow catalyst with dual defects and FeO ₅ moiety exhibits 1.4 and 2.2 times higher ammonia production activity than another two V _Br ‐featuring catalysts with coordinatively saturated FeO ₆ configuration and unsaturated FeO ₄ configuration, respectively. As revealed by experimental and theoretical calculation results, the optimized catalyst with the FeO ₅ configuration reduces the energy barrier of electron transfer from Fe 3d orbitals to antibonding orbitals of N ₂ molecules, which favors the formation of a key *NNH intermediate in the N ₂ fixation reaction and the resultant efficient ammonia production.

Exploring unique single‐atom sites capable of efficiently reducing O₂ to H₂O₂ while being inert to H₂O₂ decomposition under light conditions is significant for H₂O₂ photosynthesis, but it remains challenging. Herein, we report the facile design and fabrication of polymeric carbon nitride (CN) decorated with single‐Zn sites that have tailorable local coordination environments, which is enabled by utilizing different Zn salt anions. Specifically, the O atom from acetate (OAc) anion participates in the coordination of single‐Zn sites on CN, forming asymmetric Zn−N₃O moiety on CN (denoted as CN/Zn−OAc), in contrast to the obtained Zn−N₄ sites when sulfate (SO₄) is adopted (CN/Zn−SO₄). Both experimental and theoretical investigations demonstrate that the Zn−N₃O moiety exhibits higher intrinsic activity for O₂ reduction to H₂O₂ than the Zn−N₄ moiety. This is attributed to the asymmetric N/O coordination, which promotes the adsorption of O₂ and the formation of the key intermediate *OOH on Zn sites due to their modulated electronic structure. Moreover, it is inactive for H₂O₂ decomposition under both dark and light conditions. As a result, the optimized CN/Zn−OAc catalyst exhibits significantly improved photocatalytic H₂O₂ production activity under visible light irradiation.

Exploring unique single‐atom sites capable of efficiently reducing O₂ to H₂O₂ while being inert to H₂O₂ decomposition under light conditions is significant for H₂O₂ photosynthesis, but it remains challenging. Herein, we report the facile design and fabrication of polymeric carbon nitride (CN) decorated with single‐Zn sites that have tailorable local coordination environments, which is enabled by utilizing different Zn salt anions. Specifically, the O atom from acetate (OAc) anion participates in the coordination of single‐Zn sites on CN, forming asymmetric Zn−N₃O moiety on CN (denoted as CN/Zn−OAc), in contrast to the obtained Zn−N₄ sites when sulfate (SO₄) is adopted (CN/Zn−SO₄). Both experimental and theoretical investigations demonstrate that the Zn−N₃O moiety exhibits higher intrinsic activity for O₂ reduction to H₂O₂ than the Zn−N₄ moiety. This is attributed to the asymmetric N/O coordination, which promotes the adsorption of O₂ and the formation of the key intermediate *OOH on Zn sites due to their modulated electronic structure. Moreover, it is inactive for H₂O₂ decomposition under both dark and light conditions. As a result, the optimized CN/Zn−OAc catalyst exhibits significantly improved photocatalytic H₂O₂ production activity under visible light irradiation.