NiFeP nanoflakes composite with CoP on carbon cloth as flexible and durable electrocatalyst for efficient overall water splitting

: High-performance and earth-abundant NiFeP is an excellent bifunctional catalyst for water splitting in acidic and alkaline environments, and NiFeP nanoflakes on CoP layer composite with a conductive carbon cloth (CC) substrate as the trunk-leaf flexible structure (NiFeP/CoP/CC) is prepared by direct high-temperature phosphorization. Overpotentials of only 96.38 and 78.80 mV are required in hydrogen evolution reaction in 1 M KOH and 0.5 M H2SO4, respectively, to generate an electrocatalytic current density of 10 mA cm-2. A small Tafel slope of 70.67 and 63.21 mV per decade are also observed from NiFeP/CoP/CC revealing a Volmer-Heyrovsky mechanism in both media. The electrocatalyst also delivers excellent oxygen evolution reaction performance in the alkaline environment and long-term electrochemical durability for at least 24 h in electrolytes over a wide pH range. A device is assembled with two identical flexible ultrathin NiFeP/CoP/CC as both the anode and cathode in 1 M KOH driven by a set of 1.6 V solar cells. During 32 h of electrolysis, the results show that the current of our electrodes maintains 80% performance at a constant voltage of 1.7 V for 32 h, and the NiFeP/CoP/CC anodes and cathodes have large potential in industrial alkaline water splitting.