Metal-free red phosphorus-black phosphorus/carbon nanotubes heterostructured electrocatalyst for efficient oxygen evolution reaction

Black phosphorus (BP) has attracted a lot of interest in the fields of oxygen evolution reaction (OER). Nevertheless, in terms of single use of BP as a catalyst, the inherent instability and poor conductivity of BP often limit further improvement of OER catalytic performance. Herein, we report a method using mechanical shear force to fully mix the carbon nanotubes (CNTs) and red phosphorus powder (RP) to obtain a hybrid dimensional (RP-BP/CNTs) heterostructured metal-free electrocatalyst with excellent OER performance in alkaline media. During the ball milling process, some RP is transformed into BP due to shear stress and high-temperature in-situ phase transformation. Meantime, a large number of defects in CNTs cut by ball milling combine with the lone pair of BP to form a P–C bond, resulting in a heterojunction structure. By rational interface engineering, the hybridisation of RP-BP and CNTs improves the electroconductivity and has excellent durability. The results demonstrate that RP-BP/CNTs heterostructure shows good OER performance with a low overpotential of 263 mV vs. RHE at a current density of 10 mA cm −2 , lower than that of commercial RuO 2 (310 mV vs. RHE, 10 mA cm −2 ). The small Tafel slope indicates that the catalyst has higher catalytic performance, while the stable structure ensures its long-term durability. • Simple ball-milling method was used to prepare RP-BP/CNTs heterostructured metal-free electrocatalyst. • RP-BP/CNTs were in-situ formed through P–C and P–O–C bonds. • The hybridisation of RP-BP and CNTs improves the electroconductivity and has excellent durability. • RP-BP/CNTs shows high electro-catalytic OER activity in alkaline condition.