Catalytic hydrogen production from alkaline formaldehyde aqueous solution is a promising route to supply hydrogen on a large scale for practical applications. Producing highly efficient and low-cost catalysts is the main challenge for future development of the hydrogen economy through this route. In this paper, PdPt concave nanostructures supported on reduced graphene oxide (rGO) nanosheets are facilely obtained through chemical etching of PdPt nanocubes with nitric acid. By adjusting the Pd:Pt ratio of the nanocubes, PdPt alloy nanostructures with different degrees of concavity are obtained as a result of different etching kinetics. The as-obtained rGO supported concave nanostructures serve as highly efficient catalysts in H₂ production from alkaline formaldehyde aqueous solution. On one hand, through adjusting the Pd:Pt molar ratio, a synergistic effect between Pd and Pt is realized to enhance the catalytic activity. On the other hand, the surface concave structures of the PdPt nanocrystals offer a high density of low-coordinated atoms, serving as highly active sites for the catalytic H₂ production reaction. Furthermore, rGO nanosheets as a support are found to prevent the aggregation of metal nanocrystals and to improve the catalytic activity and stability. Based on the surface composition and structure optimization, the as-obtained rGO supported Pd₉₀Pt₁₀ octapods achieved the highest average hydrogen production rate of 0.85 mmol g_cat⁻¹ min⁻¹, about 9 times higher than that of pure Pt nanoparticles. Also, the advantages of the rGO-Pd₉₀Pt₁₀ COPs are highlighted by the minimal Pt content and excellent catalytic stability during successive cyclic processes. This work not only highlights the shape-controlled synthesis of concave metal nanocrystals through adjustment of the etching kinetics, but also underlines the importance of the collaborative design of the surface structure and composition as well as the catalyst support in realizing highly efficient hydrogen generation.

中文翻译：

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将石墨烯负载的PdPt合金纳米立方体化学刻蚀成凹形纳米结构，以增强碱性甲醛水溶液中催化氢的产生

由碱性甲醛水溶液催化制氢是为实际应用大规模提供氢的有希望的途径。通过这种途径，生产高效和低成本的催化剂是氢经济未来发展的主要挑战。在本文中，通过用硝酸化学刻蚀PdPt纳米立方体，可以轻松地获得还原氧化石墨烯（rGO）纳米片上负载的PdPt凹形纳米结构。通过调整钯：所述纳米立方体的Pt比率，PDPT合金纳米结构具有不同程度的凹的作为不同的蚀刻动力学的结果而获得。所获得的rGO负载的凹形纳米结构可作为H _2中的高效催化剂由碱性甲醛水溶液生产。一方面，通过调整钯：铂的摩尔比，实现Pd和Pt之间的协同效应，以提高催化活性。另一方面，PdPt纳米晶体的表面凹入结构提供了高密度的低配位原子，充当了催化H ₂产生反应的高活性位点。此外，发现rGO纳米片作为载体可防止金属纳米晶体的聚集并改善催化活性和稳定性。根据表面组成和结构优化，所获得的rGO负载的Pd ₉₀ Pt ₁₀八足体的最高平均产氢速率为0.85 mmol g_猫^-1 min ^-1，比纯Pt纳米颗粒高约9倍。同样，rGO-Pd ₉₀ Pt ₁₀ COPs的优点还在于，在连续的循环过程中，Pt含量最低，催化稳定性极佳。这项工作不仅强调了通过调节蚀刻动力学来控制凹形金属纳米晶体形状控制的合成，而且强调了协同设计表面结构和成分以及催化剂载体在实现高效氢生成方面的重要性。