Low-loading of oxidized platinum nanoparticles into mesoporous titanium dioxide for effective and durable hydrogen evolution in acidic media

Abstract

Low-loading of oxidized platinum nanoparticles (0.1–0.5 wt%) was incorporated into mesoporous titanium dioxide support (Ptx/meso-TiO2) via evaporation self-assembly (ESA) approach followed by a two-step calcination processes. The physicochemical characterizations showed that the oxidized Ptx/meso-TiO2 catalysts exhibit high surface area around 200 m2/g and Pt nanoparticles having an average size of 3.0 nm are uniformly incorporated into the mesoporous TiO2 matrix with the existence of Pt(II) and Pt(IV) oxidation states. The Ptx/meso-TiO2 electrocatalysts showed an enhanced electrocatalytic activity with hydrogen evolution onset potential at −10 mV vs. RHE, Tafel slope of −110 mV/dec, small charge transfer resistance, and mass activity that reaches up to 25.7 A/mgPt at −300 mV vs. RHE. The hydrogen evolution mass activity of Ptx/meso-TiO2 electrocatalysts is significantly more efficient than the commercial Pt/C catalysts and Pt nanoparticles supported on nanostructured carbon substrates. Moreover, the Ptx/meso-TiO2 electrocatalysts exhibit excellent durability for a 24-hour electrolysis in acid solution with a further current activation during the prolonged electrolysis. The enhanced mass activity and durability are attributed to the substrate mesoporosity, uniform distribution and strong bonding between the oxidized Pt nanoparticles and the TiO2 substrate. These results demonstrate the promise of the mesoporous TiO2 substrate modified with low loading of platinum nanoparticles for energy conversion technologies. Keywords: Oxidized Pt nanoparticles, Mesoporous TiO2, Electrocatalyst, Hydrogen evolution