Self‐Supported Mesoporous Iron Phosphide with High Active‐Site Density for Electrocatalytic Hydrogen Evolution in Acidic and Alkaline Media

Abstract

Developing low‐cost and highly active electrocatalysts for the hydrogen evolution reaction (HER) is urgently desired. We fabricated a mesoporous FeP self‐supported electrode (meso‐FeP/CC) through a facile and mild sol‐gel method. The mesoporous FeP self‐supported electrode displays superior HER electrocatalytic activity, requiring low overpotentials of 57 and 84 mV to drive 10 mA cm−2 in acidic and alkaline electrolyte, respectively. Meanwhile, the as‐prepared electrode exhibits fast kinetics with a small Tafel slope (acidic media: 42 mV dec−1 and alkaline media: 60 mV dec−1). The excellent catalytic performance of the electrode benefits from mesoporous framework with a large surface area (74.1 m2 g−1) and highly conductive self‐supported structure. The former endows the catalyst with a large active‐site density (3.5×1018 site per mg) and substantial accessible mesopores, and the latter accelerates reaction kinetics. This work offers a new avenue for rational designing high‐efficiency FeP HER electrocatalysts.

Metal–organic framework‐derived phosphide nanomaterials for electrochemical applications

“…The former equips the catalyst with an outstanding active-site density (3.5 × 10 18 site per mg) and massively available mesopores, and the latter optimizes reaction kinetics. 161 To clarify Gosh's view, here is another analogy. Charge separation between the P δ− and Ni δ+ sites in different nickel-phosphorus phases deserves to be emphasized so as to obtain satisfactory catalytic reaction results.…”

“…The superior catalytic behavior of the electrode induced by the mesoporous framework is accompanied by a large surface area (74.1 m 2 g −1 ) and self‐supported highly conductive architecture. The former equips the catalyst with an outstanding active‐site density (3.5 × 10 18 site per mg) and massively available mesopores, and the latter optimizes reaction kinetics 161 . To clarify Gosh's view, here is another analogy.…”

“…160 Moreover, Huang et al prepared a mesoporous FeP self-supported electrode (meso-FeP/CC) using a simple approach, which was mild and facile, and did not need to be strictly treated in a corrosive environment or high temperatures. 161 Through an electrochemical activation approach, cobalt phosphides (CoPs) were successfully prepared to improve the behavior of MP-based catalysts for OER. 162 Ghosh et al synthesized nickel phosphide phases, Ni 2 P, Ni 12 P 5 , and Ni 5 P 4, through colloidal thermal decomposition.…”

“…The highest current potential of the cathode reduction of Fe 2 P/ NPC, Co 2 P/NPC, and Ni 2 P/NPC is 0.90, 0.81, and 0.79 V versus RHE, respectively. The NPC without MPs shows a poorer activity for ORR, whose highest and the half-wave Meso-FeP/CC 10 57 60 in alkaline media [161] Abbreviations: CC, carbon cloth; HER, hydrogen evolution reaction; HNB, hollow nanobrick; NF, nickel foam. potentials are 0.75 and 0.60 V, respectively, compared with RHE.…”

“…The Ni 2 P of nanocrystalline was fabricated by a solid chemical formation of Ni oxalate when sodium hypophosphite was present in a thermal reaction 160 . Moreover, Huang et al prepared a mesoporous FeP self‐supported electrode (meso‐FeP/CC) using a simple approach, which was mild and facile, and did not need to be strictly treated in a corrosive environment or high temperatures 161 . Through an electrochemical activation approach, cobalt phosphides (CoPs) were successfully prepared to improve the behavior of MP‐based catalysts for OER 162 .…”