HIGH PERFORMANCE EARTH-ABUNDANT ELECTROCATALYSTS FOR HYDROGEN EVOLUTION REACTION AND OTHER REACTIONS
Electrodes for catalyzing electrochemical reactions (e.g., the hydrogen evolution reaction) are provided. The electrode may comprise a ternary pyrite-phase transition metal phosphochalcogenide (e.g., CoPS) disposed on a substrate, wherein the ternary pyrite-phase transition metal phosphochalcogenide is a solid material of a ternary compound of a transition metal, phosphorous (P), and a chalcogen, the solid material characterized by a substantially single, ternary alloy phase having a pyrite crystal structure. Methods of using and making the electrodes are also provided.
1 . An electrode for catalyzing an electrochemical reaction, the electrode comprising a ternary pyrite-phase transition metal phosphochalcogenide disposed on a substrate, wherein the ternary pyrite-phase transition metal phosphochalcogenide is a solid material of a ternary compound of a transition metal, phosphorous (P), and a chalcogen, the solid material characterized by a substantially single, ternary alloy phase having a pyrite crystal structure.
2 . The electrode of claim 1 , wherein the chemical species at the surface of the solid material are substantially the same as the chemical species in the bulk of the solid material.
3 . The electrode of claim 1 , wherein the ternary pyrite-phase transition metal phosphochalcogenide is a ternary pyrite-phase cobalt phosphochalcogenide, a ternary pyrite-phase nickel phosphochalcogenide, or combinations thereof.
4 . The electrode of claim 1 , wherein the ternary pyrite-phase transition metal phosphochalcogenide is ternary pyrite-phase cobalt phosphosulfide, ternary pyrite-phase cobalt phosphoselenide, ternary pyrite-phase nickel phosphosulfide, ternary pyrite-phase nickel phosphoselenide, or combinations thereof.
5 . The electrode of claim 1 , wherein the ternary pyrite-phase transition metal phosphochalcogenide has a formula MPX, wherein M is a transition metal selected from Co, Ni, Fe, and Mn; P is phosphorous; and X is a chalcogen selected from S, Se, and Te.
6 . The electrode of claim 5 , wherein M is a transition metal selected from Co and Ni; P is phosphorous; and X is a chalcogen selected from S and Sc.
7 . The electrode of claim 5 , wherein the ternary pyrite-phase transition metal phosphochalcogenide is CoPS, CoPSe, NiPSe, or combinations thereof.
8 . The electrode of claim 7 , wherein the NiPSe is Se-doped NiP 2 .
9 . The electrode of claim 1 , wherein the solid material is in the form of nanostructures.
10 . The electrode of claim 9 , wherein the nanostructures are nanoparticles, nanowires, nanoplates, or combinations thereof.
11 . The electrode of claim 1 , wherein the substrate is a carbon substrate, a metal substrate or a glass substrate.
12 . The electrode of claim 1 , wherein the substrate comprises a semiconductor capable of absorbing light to produce free electrons.
13 . The electrode of claim 1 , wherein the transition metal is alloyed with one or more other transition metals such that the ternary pyrite-phase transition metal phosphochalcogenide is an alloyed ternary pyrite-phase transition metal phosphochalcogenide.
14 . The electrode of claim 13 , wherein the alloyed ternary pyrite-phase transition metal phosphochalcogenide has a formula M 1 M 2 PX, wherein M 1 and M 2 are transition metals independently selected from Co, Ni, Fe, and Mn; P is phosphorous; and X is a chalcogen selected from S, Se, and Te.
15 . An electrochemical reaction system comprising a reaction cell configured to contain a fluid comprising an oxidant to be reduced; the electrode of claim 1 in contact with the fluid; and a counter electrode.
16 . A method for catalyzing an electrochemical reaction, the method comprising: exposing an electrode to a fluid comprising an oxidant to be reduced in the presence of free electrons, wherein the electrode comprises a ternary pyrite-phase transition metal phosphochalcogenide disposed on a substrate, wherein the ternary pyrite-phase transition metal phosphochalcogenide is a solid material of a ternary compound of a transition metal, phosphorous (P), and a chalcogen, the solid material characterized by a substantially single, ternary alloy phase having a pyrite crystal structure, whereby the free electrons induce the reduction of the oxidant at the ternary pyrite-phase transition metal phosphochalcogenide-fluid interface to form a reduction product.
17 . The method of claim 16 , wherein the free electrons are generated by applying an electrical potential across the electrode and a counter electrode in electrical communication with the electrode.
18 . The method of claim 16 , wherein the substrate comprises a semiconductor capable of absorbing light to produce free electrons, and further wherein the free electrons are generated by exposing the electrode to the light.
19 . The method of claim 16 , wherein the electrochemical reaction is the hydrogen evolution reaction, the fluid is an aqueous electrolyte solution, the oxidant comprises hydrogen ions, and the reduction product comprises hydrogen gas.
20 . A method for making an electrode, the method comprising exposing a transition metal-containing precursor disposed on a substrate to a chalcogen-phosphorous atmosphere at an elevated temperature and for a period of time sufficient to convert the transition metal-containing precursor to a ternary pyrite-phase transition metal phosphochalcogenide, wherein the ternary pyrite-phase transition metal phosphochalcogenide is a solid material of a ternary compound of a transition metal, phosphorous (P), and a chalcogen, the solid material characterized by a substantially single, ternary alloy phase having a pyrite crystal structure.