Facile synthesis of cobalt phosphide nanoparticles as highly active electrocatalysts for hydrogen evolution reaction.

• Develop new CoP nanocrystals by phosphating the Co 3 O 4 nanocubes precursor. • New type of non-metallic HER catalyst with initial potential of only 87 mV. • Self-assembled CoP nanocrystals with good catalytic performance. • Provide new way for preparing efficient and inexpensive HER electrocatalysts. Electrocatalytic water splitting reactions include hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). It provides an effective method for producing high-purity hydrogen as a sustainable energy source. In order to solve the growing energy shortage and environmental damage, the development and synthesis of efficient and inexpensive hydrogen evolution reaction (HER) electrocatalysts is urgently needed. Traditional reaction catalysts such as Pt/Rh/Ir and their oxides (such as IrO 2 , RuO 2) have limited their wide application as electrocatalysts due to their high prices and small reserves. In this work, CoP nanocrystals by phosphating the Co 3 O 4 nanocubes precursor were successfully synthesized. CoP nanocrystals are a new type of non-metallic HER catalyst that can work under alkaline conditions. Its initial potential is only 87 mV at a current density of 10 mA cm−2, and the Tafel slope is 105 mV dec−1. The catalyst can maintain the catalytic performance for 12 h in 1 M KOH solution, and the performance can still be maintained above 95.44%. [ABSTRACT FROM AUTHOR]