LAUSR

The catalytic properties of noble metal nanocrystals can be tuned via engineering their structures. Nanocrystals with fractal structures are fascinating catalysts regarding their large surface area-to-volume ratios, large numbers of edges and corners, which can be tuned simultaneously by their hierarchical ordering. However, it is still a great challenge to control the hierarchical ordering of noble metal fractal nanocrystals and their formation mechanism is not fully understood. Herein, we report a facile solvothermal method for the direct preparation of a unique single-crystal Rh-hyperbranched structure, which consists of hierarchically ultrathin nanoplates with threefold symmetry, large surface area and high density of low-coordinated edge/corner sites. Importantly, the hierarchical ordering can be readily tuned by changing the composition of solvent. In addition, we found the as-prepared single-crystal hyperbranched Rh nanoplates possessed great structure stability, and exhibited better catalytic performance towards both ethanol electrooxidation and hydrogenation of styrene than the commercial Rh black, which can be attributed to the large surface area and high-dentisty of edge/corner sites.摘要贵金属纳米晶的催化性质与其结构密切相关. 比表面积越大、配位不饱和的边角原子密度越高, 贵金属纳米晶在催化反应过程中表现出的性能往往越优异. 相比于常见的具有完整几何形貌的贵金属纳米晶, 具有多重分级结构特征的超支化贵金属纳米晶拥有更大的比表面积以及更丰富的配位不饱和的活性位点, 因此被认为是一种潜在的性能优异的催化剂. 但这种具有多重分级结构特征的超支化贵金属纳米晶无论是在生长机理研究还是可控制备上都还存在巨大的挑战. 本文通过简单的湿化学法成功制备出一种具有多重分级结构特征的超支化Rh纳米薄片. 该产物由三角形纳米片在扩散限制条件下分级生长形成, 整体呈现三次对称性的单晶特征. 研究表明, 该纳米结构不仅具有出色的结构稳定性, 而且其生长级数可通过反应溶剂比例的简单调节进行调控, 从而实现Rh纳米薄片比表面积和位于边/角活性位点的原子比例的调控. 由于拥有更大的比表面积以及更为丰富的配位不饱和的活性位点, 这种具有多重分级结构的超支化Rh纳米薄片在乙醇电催化氧化和苯乙烯催化加氢催化反应中展现出了比目前主流商业催化剂Rh黑更为优异的催化活性.