The "edge-free" monolayer MoS2 films supported by 3D nanoporous gold show high catalytic activities towards hydrogen evolution reaction (HER), originating from large out-of-plane strains that are geometrically required to manage the 3D curvature of bicontinuous nanoporosity. The large lattice bending leads to local semiconductor-to-metal transition of 2H MoS2 and the formation of catalytically active sites for HER.
We fabricated a robust electrocatalyst by chemically depositing an ultrathin layer of amorphous molybdenum sulfide on the internal surface of dealloyed nanoporous gold. The catalyst exhibits superior electrocatalysis toward hydrogen evolution reaction in both acidic and neutral media with 2-6 times improvement in catalytic activies compared to other molybdenum sulfide based materials.
A nanoporous PdNi (np‐PdNi) bimetallic catalyst fabricated by electrochemically dealloying a Pd20Ni80 alloy in an acid solution is reported. Residual Ni in the nanoporous alloy can be controlled by tuning dealloying potentials and the electrocatalysis of the np‐PdNi shows evident dependence on Ni concentrations. With ∼9 at.% Ni, the np‐PdNi bimetallic catalyst presents superior electrocatalytic performances in methanol and formic acid electro‐oxidation as well as oxygen reduction in comparison with commercial Pd/C and nanoporous Pd (np‐Pd). The excellent electrocatalytic properties of the dealloyed np‐PdNi bimetallic catalyst appear to arise from the combined effect of unique bicontinuous nanoporosity and bimetallic synergistic action.
Electrochemical energy storage: The performance of MnO2 as a pseudo‐capacitive material was enhanced by doping electrodeposited MnO2 with physically deposited gold atoms (see picture). The resulting MnO2 electrodes showed an enhanced electronic conductivity and a remarkable stability under voltammetric cycling.
We report for the first time the highly selective semihydrogenation of alkynes using the unsupported nanoporous gold (AuNPore) as a catalyst and organosilanes with water as a hydrogen source. Under the optimized reaction conditions, the present semihydrogenation of various terminal- and internal-alkynes affords the corresponding alkenes in high chemical yields and excellent Z-selectivity without any over-reduced alkanes. The use of DMF as solvent, which generates amines in situ, or pyridine as an additive is crucial to suppress the association of hydrogen atoms on AuNPore to form H(2) gas, which is unable to reduce alkynes on the unsupported gold catalysts. The AuNPore catalyst can be readily recovered and reused without any loss of catalytic activity. In addition, the SEM and TEM characterization of nanoporosity show that the AuNPore catalyst has a bicontinuous 3D structure and a high density of atomic steps and kinks on ligament surfaces, which should be one of the important origins of catalytic activity.
Dealloyed nanoporous metals have attracted much attention because of their excellent catalytic activities toward various chemical reactions. Nevertheless, coarsening mechanisms in these catalysts have not been experimentally studied. Here, we report in situ atomic-scale observations of the structural evolution of nanoporous gold during catalytic CO oxidation. The catalysis-induced nanopore coarsening is associated with the rapid diffusion of gold atoms at chemically active surface steps and the surface segregation of residual Ag atoms, both of which are stimulated by the chemical reaction. Our observations provide the first direct evidence that planar defects hinder nanopore coarsening, suggesting a new strategy for developing structurally stable and highly active heterogeneous catalysts.
A binder-free self-grown oxy-hydroxide@nanoporous Ni-Mn hybrid electrode with high capacitance and cyclic stability is fabricated by electrochemical polarization of a dealloyed nanoporous Ni-Mn alloy. Combined with the low material costs, high electrochemical stability, and environmentally friendly nature, this novel electrode holds great promise for applications in high-capacity commercial supercapacitors.
Composition‐controlled fabrication of bimetallic catalysts is of significance in electrochemical energy conversion and storage. A novel nanoporous Pt‐Cu bimetallic catalyst with a Pt skin and a Pt‐Cu core, fabricated by electrochemically dealloying a bulk Pt‐Cu binary alloy using a potential‐controlled approach, is reported. The Pt/Cu ratio of the dealloyed nanoporous catalyst can be readily adjusted in a wide composition range by only controlling dealloying potential. The electro‐catalytic performance of the nanoporous Pt‐Cu catalyst shows evident dependence on Pt/Cu ratio although the surfaces of all the nanoporous catalysts are characterized to be covered by pure Pt. With optimal compositions, the dealloyed nanoporous Pt‐Cu catalyst possesses enhanced electrocatalytic activities toward oxygen reduction reaction and formic acid oxidation in comparison with the commercial Pt/C catalyst.
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