Hongjing Wang,Tongqing Zhou,Shan Xu,Kai Deng,Hongjie Yu,You Xu,Xiaonian Li,Ziqiang Wang,Liang Wang
The development of effective and stable cathode electrocatalysts is highly desired for fuel cells. Controlling the composition and morphology of Pd-based materials can provide a great opportunity to improve their oxygen reduction reaction (ORR) performance. Here, we report the synthesis of hexagonal close-packed (hcp) Pd2B nanosheet assemblies (Pd2B NAs) via the boronation reaction between as-synthesized Pd NAs and N,N-dimethylformamide. The hcp Pd2B NAs with uniform pore distribution can provide sufficient active sites for ORRs. The insertion of B atoms can induce the phase transition from face-centered cubic structure to hcp structure, as the most thermodynamically stable phase in the Pd-B alloy, which is beneficial for enhancing the ORR stability and toxicity resistance. Therefore, the hcp Pd2B NAs exhibit superior mass activity, specific activity and excellent stability for ORR. The present strategy of boron-intercalation-triggered crystalline transition of Pd-based nanomaterials is valuable for the design of metal–nonmetal catalysts with enhanced performance.
You Xu,Mengying Liu,Tianlun Ren,Shengqi Wang,Tiantian Liu,Ziqiang Wang,Xiaonian Li,Liang Wang,Hongjing Wang
The hydrogen evolution reaction (HER) is the crucial cathodic half-reaction in electrocatalytic water splitting systems. The development of highly efficient catalysts that can trigger proton reduction with minimal overpotential and have fast kinetics is pivotal for sustainable hydrogen production by means of the HER. Crystal phase engineering and surface functionalization as feasible strategies have attracted growing interest in modulating the HER reactivity of metal-based catalysts. Herein, polyethylenimine-modified Pd2B mesoporous nanoparticles (Pd2B@PEI mNPs) with a stable hexagonal close-packed (hcp) phase were rationally designed and successfully prepared by a two-step strategy using Pd mesoporous nanoparticles as the starting material. With the dominant HER-active hcp Pd boride phase and modified surface micro-structure (e.g., increased interfacial proton concentration), the electrocatalytic activity of the as-prepared Pd2B@PEI mNPs for hydrogen evolution in acid electrolyte exceeds those of unmodified Pd2B mNPs and even commercial Pt/C. This study provides new insights for catalyst design through collaborative interface engineering and component modulation.
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