Three-dimensional metal–organic framework derived porous CoP₃ concave polyhedrons as superior bifunctional electrocatalysts for the evolution of hydrogen and oxygen

Abstract

Developing low-cost and highly-efficient non-precious metal bifunctional electrocatalysts towards the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is an attractively alternative strategy to solve the environmental pollution problems and energy demands. In this study, metal-organic framework (MOF) derived porous cobalt poly-phosphide (CoP) concave polyhedrons are prepared and explored as superior bifunctional electrocatalysts for the HER and OER. The prepared MOF derived CoP concave polyhedrons show excellent electrocatalytic activity and stability towards the HER and OER in both acidic and alkaline media, with the Tafel slopes of 53 mV dec and 76 mV dec and a current density of 10 mA cm at the overpotentials of -78 and 343 mV for the HER and OER, respectively, which are remarkably superior to those of the transition metal phosphides (TMPs) and comparable to those of the commercial precious metal catalysts. In addition, they also offer efficient catalytic activities and durabilities under neutral and basic conditions for the HER. The results of our study may shed light on the direction towards highly efficient bifunctional TMP electrocatalysts with high phosphorous component.

Electrocatalysts for Hydrogen Evolution in Alkaline Electrolytes: Mechanisms, Challenges, and Prospective Solutions

“…Among various transition metals, few are more prominent due to their high activity, e.g., Ni‐,78, 95, 102 Co‐,79, 93, 103 Fe‐, Mn‐104, 105 Mo‐, and W‐based catalysts 57, 106. To make the discussion simpler and for easy comparison, these materials is divided in to two classes, i.e., single‐metal and mixed‐metal catalysts.…”

“…Apart from Ni‐based catalysts, Co‐based catalysts (such as metallic Co and its oxides, phosphides, and sulfides), especially cobalt phosphides have attracted extensive attention as novel and efficient HER electrocatalysts for alkaline electrolytes due to their superb electrical conductivity and good durability 55, 103. As an example, when 3D porous CoP 3 concave polyhedrons were extracted from metal‐organic frameworks (MOFs), an excellent electrocatalytic activity was observed with better durability in alkaline medium 103.…”

“…As an example, when 3D porous CoP 3 concave polyhedrons were extracted from metal‐organic frameworks (MOFs), an excellent electrocatalytic activity was observed with better durability in alkaline medium 103. Thus, designing open porous structure brings an exciting advancement in developing highly efficient electrocatalysts for alkaline HER.…”

Design Strategies toward Advanced MOF‐Derived Electrocatalysts for Energy‐Conversion Reactions

“…[16] Currently, precious-metal-based catalysts (i.e., Ir, IrO 2 , and RuO 2 ) are the benchmark electrocatalysts for the OER. [15,16] Again, rationally designed materials derived from MOFs have been widely reported as alternative OER electrocatalysts, [35,80,[94][95][96]98,101,[113][114][115][116] and a summary of the OER performances of recent MOF-derived catalysts is listed in Table 2.…”

“…[98,101,106,[114][115][116] Among recent studies, Ahn and co-workers' report is one of the highest bifunctional catalysts for water electrolysis. [106] As presented in Figure 15a, a typical two-step approach was employed to derive carbon-incorporated porous Ni-Fe-P nanorods grown on nickel foams (porous NiFeP@C).…”