Surface engineering has been found to be effective in promoting the catalytic activities of noble-metal-based nanocatalysts. In this contribution, by using the PtCuxNi ternary alloy nanocrystal (NC) as the model catalyst, a surface tungsten(W)-doping strategy, combining a surface oxidative acid treatment protocol, can effectively boost the electrocatalytic activities of the NCs in oxygen reduction reaction. The W-doped PtCuxNi alloy catalysts show obvious enhancement in electrochemical surface area and mass activity and slightly enhanced specific activity compared with the undoped catalyst. Based on the experimental evidence, it is proposed that the W doping involves a surface reconstruction by first removing the surface Pt atoms from the NC and then reducing them back to the surface. The existence of surface Ni atoms may be crucial in promoting the catalytic activities possibly through their electronic interactions to the active sites. The durability of the W-doped PtCuxNi catalysts is also enhanced possibly due to the pinning effect of surface W atoms. Therefore, the surface engineering of PtCuxNi ternary alloy by W atoms can effectively modulate its activity and durability.

Although many previous studies have shown that the shape-control of nanocrystal (NCs) is an efficient strategy to improve the catalytic performance, these syntheses were conducted under very different conditions, which are not suitable for the shape-dependent properties studies as well as catalysis optimization. Herein, we demonstrate an effective method for the selective synthesis of well-defined PtPb NCs in a highly controllable manner. Four distinct PtPb NCs, namely PtPb peanut nanocrystals, PtPb hexagonal nanoplates, PtPb octahedra nanocrystals (ONCs) and PtPb nanoparticles have been selectively prepared in the presence of different phenols. Significantly, we found that the created PtPb NCs/C shows the shape-dependent activity with the optimized PtPb ONCs/C being the most active for the ethanol reforming to H-2, 22.4 times higher than the commercial Pt/C. The high performance of PtPb ONCs/C has been also successfully expanded into other polyhydric alcohols reformings. X-ray photoelectron spectroscopy (XPS) reveals that the high Pt(0)/Pt(II) ratio in PtPb NCs/C enhances the alcohols reforming. The density functional theory (DFT) studies show the PtPb ONCs possess the highest surface averaged electronic occupation for unit Pt-atom, matching well with XPS results. The PtPb ONCs/C also displays excellent durability with limited activity decay and negligible structure/composition changes after ten cycles. This work demonstrates an important advance in the high-level control of metallic nanostructures to tune the catalytic activities.

Three-dimensional (3D) nanoframes (NFs) with interconnected edges and large surface areas represent a new class of nanostructures with advanced catalytic performance. Herein, we report an efficient chemical strategy for the controlled synthesis of platinum-copper (Pt-Cu) rhombic dodecahedral nanocrystals (RDH NCs) with highly composition-segregated features. These solid Pt-Cu RDH NCs could be readily transformed into highly open Pt-Cu RDH nanoframes (NFs) with shapes and sizes that were not markedly changed after FeCl3 etching. All of the different Pt-Cu RDH NFs have the same PtCu3 phase but tunable sizes and different channel sizes. These important characteristics of the NFs provide them with much better performance than that observed for commercial Pt/C and Pt-Cu RDH NCs towards both the oxygen reduction reaction (ORR) and the methanol oxidation reaction (MOR). In particular, PtCu5 RDH NFs with the largest channel size of all the samples investigated exhibited the best activity towards the ORR and MOR and showed much less activity decay after durability tests. This work highlights the importance of precise control of 3D NF structures in enhancing electrocatalysis electrooxidations.

Herein, we report on unique bimetallic PtPb/Pt core/shell nanodisks consisting of structurally ordered PtPb hexagonal nanoplates as the core and the well-organized Pt as the shell, as extremely active and selective catalysts towards CH 3 OH reformation. We found that the created Pt-Pb nanodisks/C show the composition-dependent activity with the optimized PtPb 0.56 nanodisks/C being the most active for the CH 3 OH reformation to H 2 , 5.1 times higher than those of the commercial Pt/C. Significantly, only very limited carbon monoxide (CO) is produced during the CH 3 OH reformation, which is crucial for the practical application in fuel cells. The PtPb 0.56 nanodisks/C is also more active for CH 3 OH reformation than PtPb hexagonal nanoplates/C and PtPb 0.58 nanoparticles/C. X-ray photoelectron spectroscopy (XPS) results reveal that the high ratio of Pt (0) to Pt (II) in Pt-Pb nanodisks/C enhances the CH 3 OH reformation to H 2 , while the high content of Pb (0) is beneficial for decrease the CO production. Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) of CO adsorption shows that Pt-Pb nanodisks can promote the activation of CO molecules by forming the carboxylate (CO 2 δ − ) intermediates, leading to the low CO production.

For Pd‐based alloy catalysts, the selection of metallic alloying elements and the construction of composition‐gradient surface and subsurface layers are critical in achieving superior electrocatalytic activities in, e.g., the oxygen reduction reaction (ORR). Based on the Pd‐containing alloy, highly monodispersed PdCuNi ternary alloy nanocrystals are prepared through a wet‐chemical approach, and a solution‐based oxidative surface treatment protocol is utilized to activate the surface of the nanocrystals. A drastically enhanced ORR activity can be achieved by removing the surface Ni and Cu atoms through the surface treatment protocol. The treated catalyst demonstrates a mass activity of 0.45 A mg Pd −1 in alkaline medium, 5 and 2.4 times those of commercial Pt/C and Pd/C, respectively. The first‐principle calculation result suggests the critical roles of the coexistence of Ni and Cu atoms and their synergistic interaction beneath the outmost pure Pd layer in optimizing the oxygen binding energy for ORR. The calculation also suggests that the optimal binding energy of oxygen requires an appropriate Ni/Cu ratio in the subsurface layer. This work demonstrates a class of high‐performance Pt‐free ternary alloy ORR catalysts and may provide a general guideline for the structural design of Pd‐based ternary alloy catalysts.

The water-gas shift (WGS) reaction is an essential industrial reaction for upgrading hydrogen (H2) by removing carbon monoxide (CO), while highly efficient platinum (Pt)-based catalysts for WGS with simultaneously high activity and stability are still yet to be developed due to the poisoning issue during the reaction. Herein, we report on the porous PtPb peanut nanocrystals (porous PtPb PNCs) and porous PtPb octahedron nanocrystals (porous PtPb ONCs) with controllable ratios of Pt/Pb as extremely active and stable catalysts towards WGS reaction. It exhibits the composition-dependent activity with porous PtPb PNCs-40/ZnO being the most active for WGS to H2, 16.9 times higher than that of the commercial Pt/C. The porous PtPb PNCs-40/ZnO also display outstanding durability with barely activity decay and negligible structure and composition changes after ten successive reaction cycles. X-ray photoelectron spectroscopy (XPS) results reveal that the suitable binding energy of Pt 4f7/2 and the high ratio of Pt(0) to Pt(II) in porous PtPb PNCs/ZnO and porous PtPb ONCs/ZnO are crucial for the enhanced WGS activity. The CO stripping results indicate the optimized CO adsorption strength on the Pt surface ensure the excellent WGS activity and the outstanding durability. The present work demonstrates an important advance in tuning the porous metal nanomaterials as highly efficient and durable catalysts for catalysis, energy conversion and beyond.

Although explosive studies on pursuing high-performance Pt-based nanomaterials for fuel cell reactions have been carried out, the combined controls of surface composition, exposed facet, and interior structure of the catalyst remains a formidable challenge. We demonstrate herein a facile chemical approach to realize a new class of intermetallic Pt-Pb-Ni octahedra for the first time. Those nanostructures with unique intermetallic core, active surface composition, and the exposed facet enhance oxygen reduction electrocatalysis with the optimized PtPb1.12Ni0.14 octahedra exhibiting superior specific and mass activities (5.16 mA/cm2 and 1.92 A/mgPt) for oxygen reduction reaction (ORR) that are ∼20 and ∼11 times higher than the commercial Pt/C, respectively. Moreover, the PtPb1.12Ni0.14 octahedra can endure at least 15 000 cycles with negligible activity decay, showing a new class of Pt-based electrocatalysts with enhanced performance for fuel cells and beyond.

纳米颗粒制备过程中，作为包覆剂的有机酸分子中的羧基对纳米晶形貌具有调控作用。本论文尝试使用具有不同非极性基团的有机酸分子作为主要包覆剂，研究有机酸分子结构对PtCu纳米晶形貌的影响。通过研究16种具有代表性的含羧基有机酸分子作为包覆剂对PtCu纳米晶形成的影响，筛选出山梨酸（SA）、反丁烯二酸（FA）和衣康酸（IA）3种对PtCu纳米晶形成形貌具有显著影响的有机酸分子，并分别得到截角八面体、自主装团簇体及球状纳米颗粒。在此基础上，对所得不同形貌的PtCu催化剂通过电化学方法测试其催化氧分子还原反应（ORR）的催化活性，发现由FA包覆的团簇形PtCu纳米晶的面积比活度关系最高，而由IA包覆的截角八面体PtCu纳米晶的质量比活度最高。