Trace Iridium as ″Adhesive″ in PtCuIr Aerogels for Robust Methanol Electrooxidation

Abstract

PtCu-based alloy nanomaterials have shown great potential in methanol oxidation reaction (MOR) owing to the lower cost and good anti-poisoning ability. However, the dissolution of non-precious metal makes them suffer from severe stability issues, greatly impeding the practical application of direct methanol fuel cells. Herein, PtCuIr aerogels are successfully fabricated through a one-step NaBH 4 reduction strategy to anchor trace Ir on PtCu aerogels based on compositional engineering, which serves as advanced electrocatalysts to achieve enhanced electrocatalytic performance toward MOR. Particularly, the optimized PtCuIr aerogels show extraordinary stability and the mass activity maintains 71.2% of the initial value after 20,000 s chronoamperometric measurements. Density functional theory calculations certify that the doping of trace Ir considerably lowers the adsorption energy of CO-containing substances and thus enhances the MOR activity. By employing the vacancy formation energy of the surface Pt as the descriptor, it is revealed that the robust stability of PtCuIr aerogels originates mainly from the stronger bond between Ir and Pt/Cu atoms, where Ir acts as an ″adhesive″ to prevent the dissolution and leaching of atoms. The breakthrough of the highly stable MOR catalyst could open an avenue for affordable and durable fuel cells.

In situ electrochemical synthesis of Pd aerogels as highly efficient anodic electrocatalysts for alkaline fuel cells

“…12 With the features of ultralow mass density and plentiful meso-/macropores originating from the aerogel structure, and the active intrinsic electrocatalytic properties inherited from noble metals, NMAs have been broadly explored as electrocatalysts for electrochemical reactions including oxygen reduction, methanol oxidation, and CO 2 reduction, and outperformed their corresponding noble metal bulks and nanosized building blocks in electrocatalytic activity. [13][14][15][16][17][18][19][20] Typically, Pd aerogels by the assembly of Pd nanoparticles exhibited abundant pore structures, large specic surface areas of 40-108 m 2 g −1 , and low densities of 0.025-0.059 g cm −3 , which promoted the bioelectrocatalytic performance with 3 times higher activity compared to Pd nanoparticles. 21 Two different bottom-up approaches are generally proposed to realize the gelation of NMAs, namely, the one-step direct formation of NMAs by the reduction of corresponding metal salt solutions, and the two-step method of self-assembly of noble metal building blocks into NMAs with de-stabilizing agents or physical treatments.…”

Oxidative Self-Assembly of Au/Ag/Pt Alloy Nanoparticles into High-Surface Area, Mesoporous, and Conductive Aerogels for Methanol Electro-oxidation

“…Then, the current declined slowly until a quasi-steady state was attained within ∼3600 s followed by a more stable steady state after ∼14 h. The higher steady-state current density of the Au 0.166 Ag 0.288 Pt 0.546 alloy aerogel compared to that of the commercial Pt/C and precursor NPs throughout the i−t measurement reveals higher MOR activity, improved tolerance toward the poisonous/carbonaceous intermediates, and enhanced electrochemical durability. 89,90,95 The long-term stability of the alloy aerogels over the commercial Pt/C catalyst was further demonstrated by recording CVs at t = 0 h and t = 24 h of the chronoamperometric experiment (Figure 10). The mass activity (I f ) of the aerogel maintained ∼94% of the initial value at the end of the i−t measurements (24 h), while the mass activity of the commercial Pt/C catalyst subjected to the same bias of −0.3 V was reduced by more than 28% after 24 h. The ECSA of the aerogel showed a negligible change of 0.07% after the durability test, indicating that the observed loss in MOR activity (∼6%) can be attributed to the partial dissolution of the catalytic active sites and/or partial poisoning of the catalyst by the MOR intermediates.…”

Ultra-Low Content Bismuth-Anchored Gold Aerogels with Plasmon Property for Enhanced Nonenzymatic Electrochemical Glucose Sensing

“…Au nanomaterials possess great application prospects in nonenzymatic electrochemical glucose sensors due to their superior high catalytic activity and fascinating biocompatibility characteristics. − However, it has been a grand challenge to rationally design well-tailored Au-based nanomaterials to further boost the electrocatalytic sensing performance. It is well known that architecture, composition, and crystal structure/phase regulating are efficient scenarios for designing high-performance Au nanomaterials. − Among various noble metal nanomaterials, three-dimensional (3D) nanomaterials possess unique advantages that are formed spontaneously or self-assembled with one-dimensional and two-dimensional nanomaterials. , Noble metal aerogels (NMAs) as cutting-edge 3D nanomaterials own ultra-low density, large active surface area, porous nanowires structure, and self-supporting characteristics, which have glorious application prospects in electrocatalysis, sensors, and optoelectronics. − Generally, bimetallic nanomaterials are expected to improve the catalytic performance relative to single metal nanomaterials due to the synergistic effect. , Especially, the introduction of synergistic components with ultra-low content is an effective and challenging strategy to improve the performance of the catalyst of noble meal aerogels . More importantly, redistributing the electron density of catalysts and optimizing the adsorption energy of the reactant species on the catalyst surface were derived from the strong interactions between ultra-low content metals and metal support, drastically boosting the catalytic performance. , Synergistically enhanced Au aerogels via doping with ultra-low content metals may hold great promise to serve as advanced catalysts to provide great opportunities for electrocatalytic and sensing performance.…”