Supported Transition Metal Phosphides: Activity Survey for HER, ORR, OER, and Corrosion Resistance in Acid and Alkaline Electrolytes

摘要

One of the main bottle necks for the introduction of fuel cell technology in the market, is their dependency on precious metals as catalyst. Focusing on the electrochemical reactions involved, the most sluggish is the Oxygen Reduction Reaction (ORR). Significant research has been performed to optimize for the amount of the precious metal used, whilst keeping the same activity. On the other hand, many investigations have been carried out to find non-precious metal catalysts with the same performance for ORR, Oxygen Evolution Reaction (OER), Hydrogen Evolution Reaction (HER) and Hydrogen Oxidation Reaction (HOR). One of those candidates are the metal phosphides, however, these catalysts nowadays only are active for ORR, HER, OER and they have very poor activity towards the HOR. Here we present the work done related to the simple synthesis of different MP catalysts (M = Ni, Co, W, Cr and Mo); their catalytic activity towards H_2 and O_2 reactions; and their corrosion resistance in acidic and alkaline electrolytes. Co_2P was found to have a very interesting ORR catalytic behaviour and peroxide generation under alkaline and acidic conditions respectively. To understand the activity of Co_2P, an HRTEM analysis was done to understand the changes in the morphology before and after the ORR reaction.