Noble-metal hollow nanocrystals possess numerous unique advantages such as high surface-to-volume ratio and high utilization of noble metals, which make them a promising electrocatalyst for electro-oxidation of small molecules in fuel cells. Herein, we prepared bimetallic PdNi hollow nanocrystals (PdNi-HNCs) by taking advantage of the galvanic replacement reaction in an aqueous solution and developed a facile NiO-induced strategy for the controlled synthesis of PdNi-HNCs with dendritic or smooth outer shell architectures. A very short oxidation time of an amorphous Ni template is demonstrated to be the key factor to successful fabrication of the dendritic morphology. The results of electrochemical testing indicate that the electrocatalytic activities of PdNi-HNCs are highly dependent on their morphologies. The PdNi-HNCs with a rough and dendritic shell exhibit a mass activity of 1201.5 and 768.0 mA mg_Pd⁻¹ toward ethanol oxidation reaction (EOR) and formic acid oxidation reaction (FAOR), respectively, much greater than those of the commercial Pd black catalyst (502.6 and 266.3 mA mg_Pd⁻¹, respectivlely). In particular, the 1500 cyclic voltammetry cycles in alkaline solution and the 30,000 s chronoamperometry tests in acid solution suggest an enhanced long-term durability of PdNi-HNCs with dendritic nanoarchitectures. We ascribe the better catalytic activity to the hollow feature, higher specific electrochemical surface area, more abundant active sites and more appropriate electronic structure of the PdNi-HNCs with a rough and dendritic shell.

贵金属空心纳米晶体具有许多独特的优势，例如高的体积比和贵金属的高利用率，这使它们成为燃料电池中小分子电氧化的有前途的电催化剂。在这里，我们利用水溶液中的电置换反应制备了双金属PdNi中空纳米晶体（PdNi-HNCs），并开发了一种简便的NiO诱导的策略，用于以树状或光滑的外壳结构可控地合成PdNi-HNCs。非晶态Ni模板的非常短的氧化时间被证明是成功制造树枝状形态的关键因素。电化学测试结果表明，PdNi-HNCs的电催化活性高度依赖于其形态。_钯^-1朝向乙醇氧化反应（EOR）和甲酸氧化反应（FAOR）分别远大于那些商业Pd黑催化剂（502.6和266.3毫安毫克_钯^-1，respectivlely）。尤其是，在碱性溶液中的1500伏安循环和在酸性溶液中的30,000 s计时安培测试表明，具有树枝状纳米结构的PdNi-HNC具有更高的长期耐久性。我们将PdNi-HNCs的空心特征，较高的比电化学表面积，更丰富的活性位点和更合适的电子结构归因于其具有粗糙和树枝状壳的PdNi-HNCs。