Pd/FeP catalyst engineering via thermal annealing for improved formic acid electrochemical oxidation

Thermal annealing is usually employed for performance enhancement of catalysts while the reason is still unclear. Herein, performance improvement of a promising Pd/FeP system via thermal annealing to provide enhanced active sites, as a proof of concept, was demonstrated for the formic acid oxidation reaction. Two kinds of active sites of Pd and Pd@FeP were indicated in Pd/FeP catalyst by the well-recognized CO stripping technique; the low active/unstable Pd sites could be transformed into more active Pd@FeP sites via thermal annealing and electrochemical reduction. The best catalytic activity of annealed Pd/FeP catalyst was 1.6 times of fresh Pd/FeP and 2.8 times of Pd/C catalysts. A maximum catalytic efficiency increased by 65 % was revealed owing to the Pd@FeP active sites formation; as high as 55 % of the initial current was maintained after the accelerated stability test for 1000 cycles. The result helps understand the thermal annealing effect on electro-catalyst performance improvement.