Interfacial coordination bonds accelerate charge separation for unprecedented hydrogen evolution over S-scheme heterojunction

Inspired by natural photosynthesis,fabricating high-performance S-scheme heterojunction is regarded as a successful tactic to address energy and environmental issues.Herein,NH_(2)-MIL-125(Ti)/Zn_(0.5)Cd_(0.5)S/NiS(NMT/ZCS/NiS)S-scheme heterojunction with interfacial coordination bonds is successfully synthesized through in-situ solvothermal strategy.Notably,the optimal NMT/ZCS/NiS S-scheme heterojunction exhibits comparable photocatalytic H_(2)evolution(PHE)rate of about 14876.7μmol h^(−1)g^(−1)with apparent quantum yield of 24.2%at 420 nm,which is significantly higher than that of recently reported MOFs-based photocatalysts.The interfacial coordination bonds(Zn–N,Cd–N,and Ni–N bonds)accelerate the separation and transfer of photogenerated charges,and the NiS as cocatalyst can provide more catalytically active sites,which synergistically improve the photocatalytic performance.Moreover,theoretical calculation results display that the construction of NMT/ZCS/NiS S-scheme heterojunction also optimize the binding energy of active site-adsorbed hydrogen atoms to enable fast adsorption and desorption.Photoassisted Kelvin probe force microscopy,in-situ irradiation X-ray photoelectron spectroscopy,femtosecond transient absorption spectroscopy,and theoretical calculations provide sufficient evidence of the S-scheme charge migration mechanism.This work offers unique viewpoints for simultaneously accelerating the charge dynamics and optimizing the binding strength between the active sites and hydrogen adsorbates over S-scheme heterojunction.

邻苯二硫酚桥联双核双氮过渡金属配合物N—N键活化规律的理论研究

采用密度泛函理论方法研究了具有仿生固氮结构的两类化合物[Cp＊Fe（μ-η^2η^2bdt）（μ-η^1η^1Me N=NMe）Fe Cp＊]以及[Cp＊Fe（μ-SEt）2（μ-η^1η^1Me N=NMe）Fe Cp＊]的90种不同结构,调变过渡金属中心,研究不同自旋态下（单重态和三重态）具有side-on或end-on配位键型的双核双氮过渡金属配合物,基于计算结果分析了BDT（邻苯二硫酚）和乙基类型配体的不同过渡金属配合物活化双氮的程度.研究结果表明,N—N键活化程度与配合物过渡金属中心所在周期存在密切关系,更高周期对双氮的活化程度更高,同周期金属过渡金属配合物对N—N键的活化程度从第四副族至第八族呈现折线型下降,同时,过渡金属中心的外层价电子数的奇偶性对双氮的活化程度具有一定影响.此外,side-on键型对双氮的活化程度要高于end-on键型,具有不同基团的同种骨架配体对N—N键的活化能力没有明显区别。