Creating two-dimensional (2D) crystal–metal heterostructures with an ultrathin thickness has spurred increasing research endeavors in catalysis because of its fascinating opportunities in tuning the electronic state at the surface and enhancing the chemical reactivity. Here we report a novel and facile Nb⁴⁺-assisted strategy for the in situ growth of highly dispersed Pd nanoparticles (NPs) on monolayer HNb₃O₈ nanosheets (HNb₃O₈ NS) constituting a 2D Pd/HNb₃O₈ NS heterostructure composite without using extra reducing agents and stabilizing agents. The Pd NP formation is directed via a redox reaction between an oxidative Pd salt precursor (H₂PdCl₄) and reductive unsaturated surface metal (Nb⁴⁺) sites induced by light irradiation on monolayer HNb₃O₈ NS. The periodic arrangement of metal Nb nodes on HNb₃O₈ NS leads to a homogeneous distribution of Pd NPs. Density functional theory (DFT) calculations reveal that the direct redox reaction between the Nb⁴⁺ and Pd²⁺ ions leads to a strong chemical interaction between the formed Pd metal NPs and the monolayer HNb₃O₈ support. Consequently, the as-obtained Pd/HNb₃O₈ composite serves as a highly efficient bifunctional catalyst in both heterogeneous thermocatalytic and photocatalytic selective reduction of aromatic nitro compounds in water under ambient conditions. The achieved high activity originates from the unique 2D nanosheet configuration and in situ Pd incorporation, which leads to a large active surface area, strong metal–support interaction and enhanced charge transport capability. Moreover, this facile Nb⁴⁺-assisted synthetic route has demonstrated to be general, which can be applied to load other metals such as Au and Pt on monolayer HNb₃O₈ NS. It is anticipated that this work can extend the facile preparation of noble metal/nanosheet 2D heterostructures, as well as promote the simultaneous capture of duple renewable thermal and photon energy sources to drive an energy efficient catalytic process.

中文翻译：

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一种不饱和金属定点促进的方法，可构建强耦合的贵金属/ HNb ₃ O ₈纳米片，以有效地进行热/光催化还原

创建具有超薄厚度的二维（2D）晶体-金属异质结构，已激发了催化领域越来越多的研究努力，因为它在调节表面电子状态和增强化学反应性方面具有引人入胜的机会。在这里，我们报告了一种新颖且简便的Nb ⁴⁺辅助策略，用于在构成2D Pd / HNb ₃ O ₈ NS的单层HNb ₃ O ₈纳米片（HNb ₃ O ₈ NS）上原位生长高度分散的Pd纳米颗粒（NPs）异质结构复合材料，无需使用额外的还原剂和稳定剂。Pd NP的形成通过氧化钯盐前体（H ₂ PdCl ₄）与单层HNb ₃ O ₈ NS上的光辐照引起的还原性不饱和表面金属（Nb ⁴⁺）位之间的氧化还原反应。HNb ₃ O ₈ NS上金属Nb节点的周期性排列导致Pd NPs的均匀分布。密度泛函理论（DFT）计算表明，Nb ⁴⁺和Pd ²⁺离子之间的直接氧化还原反应导致形成的Pd金属NP与单层HNb ₃ O ₈载体之间发生强烈的化学相互作用。结果，得到的Pd / HNb ₃ O₈复合材料在环境条件下，在水中非均相热催化和光催化选择性还原芳香族硝基化合物中均充当高效双功能催化剂。实现的高活性源自独特的2D纳米片结构和原位Pd掺入，这导致了较大的活性表面积，强大的金属与载体相互作用以及增强的电荷传输能力。而且，这种简便的Nb ⁴⁺辅助合成路线已被证明是通用的，可用于在单层HNb ₃ O ₈上装载其他金属，例如Au和PtNS。预计这项工作可以扩展贵金属/纳米片2D异质结构的简便制备，并促进同时捕获双重可再生热能和光子能源，以驱动节能的催化过程。