Self‐Supporting Porous CoP‐Based Films with Phase‐Separation Structure for Ultrastable Overall Water Electrolysis at Large Current Density

Abstract

Stable non-noble metal electrocatalysts are of essential importance for industrial water electrolysis. Powdery electrocatalysts loaded on current collectors by binders are often designed, but easily fall off due to strong attack by bubbles at an industrial large current density (>400 mA cm −2 ). A novel strategy is developed to construct a self-supported dual-phase porous Co 2 P-Co 3 O 4 film for oxygen evolution reaction (OER) and micro-nanoporous Co 2 P film for hydrogen evolution reaction (HER) based on the electrodeposition of single-phase porous CoP film on gas-liquid-solid interface, phase separation to Co 2 P-Co, and selective oxidation/etching of the Co phase. The self-supported dual-phase Co 2 P-Co 3 O 4 catalyst exhibits good electrocatalytic activity for OER. The overpotentials are 265 and 405 mV at 20 and 200 mA cm −2 , respectively. In addition, the self-supported micro-nanoporous Co 2 P catalyst shows high catalytic activity for HER due to large active area and good wettability. Both dual-phase Co 2 P-Co 3 O 4 and micro-nanoporous Co 2 P possess ultrastability, even at a large current density of 500 mA cm −2 due to the self-supported structure. The cell voltage of water electrolysis using a self-supported Co 2 P-Co 3 O 4 ||Co 2 P electrolyzer at 500 mA cm −2 is only about 3.36 ± 0.01 V, which is much lower than that (4.31 ± 0.05 V) of the IrO 2 -Ta 2 O 5 ||Pt electrolyzer.

Multifunctional Transition Metal‐Based Phosphides in Energy‐Related Electrocatalysis

“…f) The measurements of contact angle and surface tension around the gas‐liquid interface on various samples. Reproduced with permission . Copyright 2018, John Wiley and Sons.…”

“…As expected, this 3D nanoporous Co 2 P with pores size around 30 nm presented excellent HER performance in both acidic and alkaline media. In comparison, Jiao's group reported the synthesis of micro‐nanoporous Co 2 P film by an integrated strategy (Figure e) . In detail, self‐supported CoP film with micrometer‐scale pores was first prepared by electrodeposition using hydrogen bubbles as the template.…”

Silica‐Free Synthesis of Mesoporous Co3O4/CoOxPy as a Highly Active Oxygen Evolution Reaction Catalyst

“…The charge‐transfer resistances are read as 24.5 and 45.2 Ω for M−Co 3 O 4 /CoO x P y and M−Co 3 O 4 , respectively. The enhanced charge transport kinetics after phosphorization was beneficial for the OER catalysis, and suggested the potential electronic interaction and synergistic effect between M−Co 3 O 4 and CoO x P y …”

“…The enhanced charge transport kinetics after phosphorization was beneficial for the OER catalysis, and suggested the potential electronic interaction and synergistic effect between MÀ Co 3 O 4 and CoO x P y . [57,58]…”

Self‐Supported Oxygen and Molybdenum Dual‐Doped Cobalt Phosphide Hierarchical Nanomaterials as Superior Bifunctional Electrocatalysts for Overall Water Splitting

“…However, practical application of nano/microstructured catalysts in powder forms need to be casted on the current collector with an extra polymeric binder like polytetrafluoroethylene or Nafion, which blocks the active sites, inhibits mass transport, and is easily peeled off during long‐time electrocatalysis. To address this concern, the self‐supported nano/micromaterials in situ grown on the conductive substrates including nickel foam (NF), carbon cloth (CC) and so on are desirable, in which the catalysts facilitate the penetration of the electrolyte, promote charge and ions transfer, and accelerate the bubble detachment [34–38] . Therefore, the controllable integration of self‐supported novel nano/microstructured catalysts with excellent performance for both HER and OER become one of the hottest research topics in the field.…”