Kui Li

Platinum nanoparticles partially-embedded into carbon sphere surfaces: a low metal-loading anode catalyst with superior performance for direct methanol fuel cells

Pt-based catalysts are considered as the most efficient and indispensable catalysts for methanol electro-oxidation reactions (MORs) in acidic media; however, issues linked to cost and stability impede their large-scale application. Here, we present a novel structured catalyst with Pt nanoparticles partially embedded in resorcinol-formaldehyde carbon spheres (Pt@RFC) towards MORs. Pt@RFC exhibits excellent CO-tolerance and MOR activity, and specifically, the CO electro-oxidation peak-potential is negatively shifted by ∼150 mV and the electrocatalytic activity is 2 times that of commercial Pt/C. These enhancements are due to the endowed high Pt utilization (decreased particle size) from strong metal-support interaction and the decorated electronic properties. Moreover, the firmly anchored Pt nanoparticles are prevented from possible dissolution, agglomeration and detachment during long-term use. Remarkably, after an accelerated degradation test through a 3000 cycle cyclic voltammetry test, the mass activity for Pt@RFC is well maintained and 5.8 times that of the commercial Pt/C. Upon integration into a DMFC, Pt@RFC (58.5 mW cm−2) exhibits a competitive power density at 60 °C compared to a commercial PtRu/C catalyst (52.3 mW cm−2) with only 1/3 of the noble metal loading, as well as a slower degradation rate during discharge testing. The present findings indicate that Pt@RFC might be a viable alternative as a commercial catalyst applied in DMFCs.

Promotion of Mesoporous Vanadium Carbide Incorporated on Resorcinol–Formaldehyde Resin Carbon Composites with High‐Surface‐Areas on Platinum Catalysts for Methanol Electrooxidation

Vanadium carbide incorporated on resorcinol–formaldehyde resin carbon (V8C7@RFC) was synthesized as a novel mesoporous catalyst‐support material by pyrolysis of the resorcinol–formaldehyde resin and NaVO3 mixture. The material’s BET surface area was 564 m2 g−1 and thus much higher than that of 389 m2 g−1 for the carbon powders yielded by resin carbonation. Physical characterization revealed that the supporting material possesses a mesoporous structure and Pt nanoparticles are homogeneously dispersed on the V8C7@RFC surface. Electrochemical measurements demonstrated that the V8C7‐modified Pt catalyst exhibits a negative shift of over 100 mV in the onset potential for COads electrooxidation and a dramatically enhanced activity in methanol oxidation reaction. The enhancement was mainly attributed to the electronic effect between Pt and V8C7 and the mesoporous structure providing ideal anchor sites for Pt dispersion.

Enhanced electrocatalytic performance for the hydrogen evolution reaction through surface enrichment of platinum nanoclusters alloying with ruthenium in situ embedded in carbon

The hydrogen evolution reaction is a crucial step in electrochemical water splitting. The most efficient catalysts for this reaction in acidic media are Pt based, but the high cost of Pt limits its practical applications. We developed a novel matrix architecture in which a trace amount of Pt is alloyed in situ with Ru nanoparticles uniformly and partially embedded in porous carbon spheres. The synthetic procedure is simple and efficient. Surface enrichment of metallic Pt nanoclusters on PtRu alloy nanoparticles results in weak bonding with hydrogen and rapid hydrated proton dissociation. These effects significantly increase the electrocatalytic activity in the hydrogen evolution process. This robust catalyst, with a Pt loading 99.9% less than that of a commercial Pt-based catalyst, gave a high turnover frequency (4.03 H2 s−1), a small Tafel slope (27.2 mV dec−1), and comparable overpotentials (19.7 mV and 43.1 mV), as well as achieved current densities of 10 and 100 mA cm−2, i.e., better than those obtained with commercial Pt/C catalyst, in 0.5 M H2SO4. This structure prevents nanoparticles from dissolving, agglomerating, and detaching during long-term operation; therefore there was no obvious decrease in catalytic activity after continuous reaction.