Electrochemical disproportionation strategy to in-situ fill cation vacancies with Ru single atoms

Supported single-atom catalysts(SACs)possess high catalytic activity,selectivity,and atom utilizations.However,the atom coordination environments of SACs are difficult to accurately regulate due to the high complexity of coordination site and local environment of support.Herein,we develop an in-situ electrochemical cation-exchange method to fill the cation vacancies in MnO_(2)with Ru single atoms(SAs).This obtained catalyst exhibits high mass activity,which is~44 times higher than commercial RuO2 catalyst and excellent stability,superior to the most state-of-the-art oxygen evolution reaction(OER)catalysts.The experimental and theoretical results confirm that the doped Ru can induce charge density redistribution,resulting in the optimized binding of oxygen species,and the strong covalent interaction between Ru and MnO2 for resisting oxidation and corrosion.This work will provide a new concept in the synthesis of well-defined local environments of supported SAs.

垂直交错且具有可控电子结构的NiFeP/MXene电催化剂用于高效析氧反应

具有良好析氧反应(OER)活性的层状双氢氧化物(LDHs)在储能/转化领域得到了广泛的研究.然而,导电性差、易团聚、本征活性低等特点限制了其实际应用.通过改善NiFeLDHs的本征活性和稳定性(如引入杂原子或与其他导电基质结合)以提高全解水性能,受到越来越多的关注.本文通过水热和煅烧磷化两步反应,成功合成了在碳化钛二维薄片上的垂直交错的三元相磷化镍/铁杂化物(NiFeP/MXene).优化后的NiFe P/MXene在电流密度为10 mA cm^(-2)时仅有286 mV的低过电位和较低的塔菲尔斜率35 mV dec^(-1),超过了许多现有的NiFe基催化剂的性能.进一步将NiFeP/MXene应用于碱性电解质中全解水的阳极,仅需要1.61 V的电池电压就能达到10 mA cm^(-2)的电流密度.密度函数理论(DFT)计算结果表明,无论是MXene还是磷化,都能有效调整电催化剂表面的电子结构和密度,提升d带中心的能级,从而实现对OER性能的提升.该研究为设计高性能的OER催化剂提供了新的思路.

Heterostructures of NiFe LDH hierarchically assembled on MoS_(2) nanosheets as high-efficiency electrocatalysts for overall water splitting

Typically,rational interfacial engineering can effectively modify the adsorption energy of active hydrogen molecules to improve water splitting efficiency.NiFe layered double hydroxide(NiFe LDH)composite,an efficient oxygen evolution reaction(OER)catalyst,suffers from slow hydrogen evolution reaction(HER)kinetics,restricting its application for overall water splitting.Herein,we construct the hierarchical MoS_(2)/NiFe LDH nanosheets with a heterogeneous interface used for HER and OER.Benefiting the hierarchical heterogeneous interface optimized hydrogen Gibbs free energy,tens of exposed active sites,rapid mass-and charge-transfer processes,the MoS_(2)/NiFe LDH displays a highly efficient synergistic electrocatalytic effect.The MoS_(2)/NiFe LDH electrode in 1 mol/L KOH exhibits excellent HER activity,only 98 mV overpotential at 10 mA/cm^(2).Significantly,when it assembled as anode and cathode for overall water splitting,only 1.61 V cell voltage was required to achieve 10 mA/cm^(2)with excellent durability(50 h).

A topotactic tailored synthesis of waxberry-like mixed-phase TiO_(2) hollow spheres for dye-sensitized solar cells

The waxberry-like mixed-phase TiO_(2)hollow microstructures (WMTHMs) are controllably prepared via a topotactic synthetic method,involving the synthesis of monodispersed Ca TiO_(2)precursors by a solvothermal method and subsequently transforming them into TiO_(2)through a Na_(2)EDTA-assisted ion-exchange process.The ratio of anatase-rutile is adjustable,and the two phases are connected well with each other.WMTHMs are composed of radially aligned nanorods,speeding up the electron transport.The optimum WMTHMs sample shows a specific surface area of 68.05 m^(2)/g and exhibits an excellent light scattering capacity.The cell based on WMTHMs light scattering layer obtained an optimal efficiency of 9.12%.The improvement of cell efficiency is mainly attributed to the high specific surface area,the efficient light scattering,the appropriate ratio of anatase-rutile,the staggered bandgap structure,and the convenient one-dimensional electron transport channel.