Electrocatalysis Snapshots: Materials for the Hydrogen Evolution Reaction

Late last year, we took a look at some of the new materials coming out of our global laboratories for the purpose of catalyzing the oxygen evolution reaction (OER). Part of the overall reaction for water splitting, the kinetics for this reaction are known to be a rate-limiting step in the process. The other reaction involved, no less important for the future generation of clean, sustainable energy, is the hydrogen evolution reaction (HER).

So what new materials and ideas have recently been published for HER electrocatalysis?

The use of noble metal catalysts on carbon supports is known, but the key challenge is to reduce the amount of metal used without compromising the catalytic performance of the material. One way to do this is to replace part of the noble metal content with a low-cost, earth-abundant non-noble metal, which is exactly what researchers from Zhejiang Sci-Tech University, China, have done. They used a simple electrospinning and graphitization technique to encapsulate Pt–Cu alloy nanoparticles in carbon nanofibers. The nanoparticles were found to be distributed uniformly, and the green nature of this synthesis technique is in keeping with the sustainability aspect of its intended application. Indeed, their alloy/carbon composite showed promise for HER: the alloy/nanofiber produced a Tafel slope of 68 mV dec-1, which was better than the 104 mV dec-1 slope recorded for pure Pt nanoparticle/nanofiber composites. It also showed a small overpotential of 71 mV in acidic media at a current density of 10 mA cm2. The researchers suggest that these values are the result of the synergistic interaction between the two metals, with the alloy structure helping the copper to resist the oxidation that normally limits its use in such applications.

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