Novel transition-metal phosphides@N, P-codoped carbon electrocatalysts synthesized via a universal strategy for overall water splitting

Developing highly efficient and stable bifunctional electrocatalysts plays a crucial role in water splitting reaction. Benefiting from their abundant reserves, superior conductivity and excellent intrinsic catalytic properties, transition metal phosphides (TMPs) draw wide attentions in recent years. However, most of TMPs synthesis processes are still acomplicated and dangerous as the common use of toxic and flammable phosphorus sources. Herein, we propose a universal and scalable synthetic strategy to prepare a series of nanosized transition metal phosphide encapsulated in nitrogen-phosphorus co-doped carbon (TMP@NPC) catalysts by using green and inexpensive adenosine triphosphate (ATP) as a new phosphorus source. Profiting from the in situ and confined synthetic strategy, as-prepared TMP@NPC catalysts not only show nanosized dimension, but also endow extremely intimate interaction with N, P component derived from ATP. All as-prepared TMP@NPC catalysts exhibit excellent hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activities with small overpotentials and robust capabilities. Especially, the CoP@NPC displays the lowest overpotentials of 184.35 mV and 303 mV at 10 mA cm−2 toward HER and OER in alkaline electrolyte, respectively, which also exhibits outstanding stability (over 50 h at 10 mA cm−2) in both reactions. As a proof of further application, as-prepared CoP@NPC acting as both cathode and anode shows excellent performance in overall water splitting. This work not only highlights the green and general synthesis strategy importance in designing and constructing TMPs, but also reinforces the understanding of intimate interaction in coupled hybrid electrocatalysts.