Effects of heat treatment temperature and atmosphere on electrocatalytic properties of platinum nanocrystals

Abstract

In this work, we studied effect of heat treatment temperature and atmosphere on the electrocatalytic activity and durability of catalysts platinum cubic nanocrystals (Pt NCs) supported on carbon nanotubes (Pt NCs@CNTs) toward oxygen reduction reaction (ORR) in acid solutions. The Pt NCs@CNT 300 catalysts were more active than other temperatures toward ORR, and after 20%H 2 –Ar treatment the ORR activity of Pt NCs@CNTs was more enhanced than that after pure Ar treatment. This work demonstrated that heat treatment is necessary to improve the activity and durability of Pt NCs catalysts for practical catalytic applications. • Pt NCs@CNT treated at 300 °C has higher ORR activity than others treated at different temperatures. • Pt NCs@CNT treated under 20%H 2 –Ar performed better catalytic activity than pure Ar atmosphere. • Heat treatment is necessary to improve the performance of Pt nanocrystals for catalytic applications. Platinum nanocrystals (Pt NCs) have excellent catalytic activity toward oxygen reduction reaction (ORR). The morphology ( e.g. size, facet, shape) of Pt NCs will change upon heating and the effect of this change in morphology on ORR activities of Pt NCs is unclear. In this work, the effects of heat treatment temperature and atmosphere on ORR activities of catalysts Pt NCs supported on carbon nanotubes were studied. Pt NCs were synthesized via a homogeneous aqueous chemical reduction method and then were dispersed and adsorbed onto carbon nanotubes support. It was found that after heat treatment at 300 °C, the Pt NCs have larger active surface areas, higher activity and longer durability toward ORR. And when the heat treatment was conducted in atmosphere of 20%H 2 –80%Ar (by volume), the catalysts had higher ORR activity than that heated in pure Ar gas. This work demonstrated that Pt NCs after heat treatment in a suitable atmosphere will cause a fine tuning of the surface atomic configuration, which determine the activity and long-term durability of Pt NCs catalysts.