Aqueous Suspensions of Carbon Nanomaterials with Platinum Nanoparticles for Solution-Processed Hydrogen-Producing Electrocatalysts

Proton exchange membrane (PEM) waterelectrolysis isattractingattention as a promising method for producing clean hydrogen (H-2) without emitting carbon dioxide. H-2 is producedby the reduction of protons at the cathode in a PEM electrolyzer.Platinum on carbon (Pt/C) is extensively used as a cathodic electrocatalyst;however, the aggregation of Pt in Pt/C necessitates high loading tomaintain catalytic activity. Therefore, the development of efficientH(2) production electrocatalysts with low Pt loadings isnecessary. Herein, we report the preparation of electrocatalysts consistingof solution-processed platinum nanoparticle (PtNP)/carbon nanomaterial(CNM) composites using surfactant-free aqueous-dispersed PtNPs asa dispersant for CNMs. Direct aqueous suspension by PtNPs throughnoncovalent functionalization occurs universally with single-walledcarbon nanotubes (SWCNTs), graphene, and acetylene black, yieldingthe respective composites. In particular, the PtNP/SWCNT nanocompositeelectrocatalyst with a PtNP loading of 6 & mu;g(Pt) cm(-2) exhibited a high mass activity of 89,300 A g(Pt) (-1) at 2.0 V, which is 270 times higherthan that of Pt/C (324 A g(Pt) (-1) at 2.0V) with a Pt loading of 2.8 mg(Pt) cm(-2). Furthermore, a PEM electrolyzer containing this electrocatalystexhibited a Faradaic efficiency of 99% and operated continuously for150 h at 100 mA cm(-2) at an estimated cost of US$5.3/(kgH(2)). Our findings are promising in terms of not only establishinga methodology for reducing PtNP loading to the microgram order butalso demonstrating the practical feasibility of H-2-productionelectrocatalysts for PEM electrolyzers.

Automated summary

Proton exchange membrane (PEM) water electrolysis is a promising method for clean hydrogen production. A new approach using aqueous-dispersed PtNPs as a dispersant for carbon nanomaterials (CNMs) is reported, resulting in efficient PtNP/CNM composites. The PtNP/SWCNT nanocomposite exhibits a mass activity of 89,300 A g(Pt) (-1), 270 times higher than that of Pt/C.