Phosphorus oxoanion-intercalated layered double hydroxides for high-performance oxygen evolution

Abstract

Rational design and controlled fabrication of efficient and cost-effective electrodes for the oxygen evolution reaction (OER) are critical for addressing the unprecedented energy crisis. Nickel–iron layered double hydroxides (NiFe-LDHs) with specific interlayer anions (i.e. phosphate, phosphite, and hypophosphite) were fabricated by a co-precipitation method and investigated as oxygen evolution electrocatalysts. Intercalation of the phosphorus oxoanion enhanced the OER activity in an alkaline solution; the optimal performance (i.e., a low onset potential of 215 mV, a small Tafel slope of 37.7 mV/dec, and stable electrochemical behavior) was achieved with the hypophosphite-intercalated NiFe-LDH catalyst, demonstrating dramatic enhancement over the traditional carbonate-intercalated NiFe-LDH in terms of activity and durability. This enhanced performance is attributed to the interaction between the intercalated phosphorous oxoanions and the edge-sharing MO6 (M = Ni, Fe) layers, which modifies the surface electronic structure of the Ni sites. This concept should be inspiring for the design of more effective LDH-based oxygen evolution electrocatalysts.