Self-improving electrocatalysts for gas evolution reactions

Abstract

In some embodiments, the present disclosure pertains to methods of mediating a gas evolution reaction by exposing a gas precursor to an electrocatalyst that comprises a plurality of layers with catalytic sites. The exposing results in electrocatalytic conversion of the gas precursor to a gas. Thereafter, the generated gas enhances the electrocatalytic activity of the electrocatalyst by enhancing the accessibility of the catalytic sites to the gas precursor. In some embodiments, the electrocatalyst is associated with an electrically conductive surface (e.g., an electrode) that provides electrical current. In some embodiments, the electrocatalyst is a hydrogen production electrocatalyst that converts H + to H 2 . In some embodiments, the electrocatalyst includes a transition metal dichalcogenide. Further embodiments of the present disclosure pertain to the aforementioned electrocatalysts for mediating gas evolution reactions.

What is claimed is: 
     
         1 . A method of mediating a gas evolution reaction, wherein the method comprises:
 exposing a gas precursor to an electrocatalyst comprising a plurality of layers, wherein the layers comprise catalytic sites;   wherein the exposing results in electrocatalytic conversion of the gas precursor to a gas between the layers; and   wherein the gas enhances the electrocatalytic activity of the electrocatalyst.   
     
     
         2 . The method of  claim 1 , wherein the electrocatalyst is associated with an electrically conductive surface, wherein the electrically conductive surface provides electrical current. 
     
     
         3 . The method of  claim 2 , wherein the electrically conductive surface is an electrode. 
     
     
         4 . The method of  claim 1 , wherein the gas precursor is H + , wherein the gas is H 2 , and wherein the gas evolution reaction is a hydrogen evolution reaction that converts H +  to H 2 . 
     
     
         5 . The method of  claim 1 , wherein the electrocatalyst is a hydrogen production electrocatalyst that converts H +  to H 2 . 
     
     
         6 . The method of  claim 1 , wherein the electrocatalyst comprises a transition metal dichalcogenide. 
     
     
         7 . The method of  claim 6 , wherein the transition metal dichalcogenide comprises a group V transition metal dichalcogenide. 
     
     
         8 . The method of  claim 6 , wherein the transition metal dichalcogenide comprises the following formula:
   MX 2 ,   wherein M is a transition metal, and   wherein X is a chalcogen.   
     
     
         9 . The method of  claim 8 , wherein the transition metal is selected from the group consisting of Ti, Hf, Zr, Mo, W, Ta, Nb, V, Tc, Re, Sn and combinations thereof. 
     
     
         10 . The method of  claim 8 , wherein the chalcogen is selected from the group consisting of S, Se, O, Te, and combinations thereof. 
     
     
         11 . The method of  claim 8 , wherein X is S. 
     
     
         12 . The method of  claim 1 , wherein the electrocatalyst is selected from the group consisting of TaS 2 , NbS 2 , VS 2 , and combinations thereof. 
     
     
         13 . The method of  claim 1 , wherein the layers are in the form of crystal plates. 
     
     
         14 . The method of  claim 1 , wherein the layers are separated by a distance ranging from about 0.1 nm to about 1 nm. 
     
     
         15 . The method of  claim 1 , wherein the layers are porous. 
     
     
         16 . The method of  claim 1 , wherein the catalytic sites are on surfaces of the layers. 
     
     
         17 . The method of  claim 1 , wherein the produced gas enhances the electrocatalytic activity of the electrocatalyst by enhancing the accessibility of the catalytic sites to the gas precursor. 
     
     
         18 . The method of  claim 17 , wherein the gas enhances the accessibility of the catalytic sites to the gas precursor by increasing distances between the layers, thereby making the catalytic sites more accessible to the gas precursor. 
     
     
         19 . The method of  claim 17 , wherein the produced gas enhances the electrocatalytic activity of the electrocatalyst with time. 
     
     
         20 . The method of  claim 1 , wherein the electrocatalyst has an exchange current density ranging from about 2×10 −4  A/cm 2  to about 10×10 −4  A/cm 2 . 
     
     
         21 . The method of  claim 1 , wherein the electrocatalyst has a catalyst loading that ranges from about 10 μg/cm 2  to about 100 μg/cm 2 . 
     
     
         22 . The method of  claim 1 , wherein the electrocatalyst has a Tafel slope ranging from about of 25 mV/decade to about 100 mV/decade. 
     
     
         23 . The method of  claim 1 , wherein the electrocatalyst has a current density ranging from about of 5 mA/cm 2  to about 50 mA/cm 2 . 
     
     
         24 . An electrocatalyst for mediating a gas evolution reaction,
 wherein the electrocatalyst comprises a plurality of layers, and
 wherein the layers comprise catalytic sites. 
   
     
     
         25 . The electrocatalyst of  claim 24 , wherein the electrocatalyst is associated with an electrically conductive surface, wherein the electrically conductive surface provides electrical current. 
     
     
         26 . The electrocatalyst of  claim 25 , wherein the electrically conductive surface is an electrode. 
     
     
         27 . The electrocatalyst of  claim 24 , wherein the electrocatalyst is a hydrogen production electrocatalyst that converts H +  to H 2 . 
     
     
         28 . The electrocatalyst of  claim 24 , wherein the electrocatalyst comprises a transition metal dichalcogenide. 
     
     
         29 . The electrocatalyst of  claim 28 , wherein the transition metal dichalcogenide comprises a group V transition metal dichalcogenide. 
     
     
         30 . The electrocatalyst of  claim 28 , wherein the transition metal dichalcogenide comprises the following formula:
   MX 2 ,   wherein M is a transition metal, and   wherein X is a chalcogen.   
     
     
         31 . The electrocatalyst of  claim 30 , wherein the transition metal is selected from the group consisting of Ti, Hf, Zr, Mo, W, Ta, Nb, V, Tc, Re, Sn and combinations thereof. 
     
     
         32 . The electrocatalyst of  claim 30 , wherein the chalcogen is selected from the group consisting of S, Se, O, Te, and combinations thereof. 
     
     
         33 . The electrocatalyst of  claim 30 , wherein X is S. 
     
     
         34 . The electrocatalyst of  claim 24 , wherein the electrocatalyst is selected from the group consisting of TaS 2 , NbS 2 , VS 2 , and combinations thereof. 
     
     
         35 . The electrocatalyst of  claim 24 , wherein the layers are in the form of crystal plates. 
     
     
         36 . The electrocatalyst of  claim 24 , wherein the layers are separated by a distance ranging from about 0.1 nm to about 1 nm. 
     
     
         37 . The electrocatalyst of  claim 24 , wherein the layers are porous. 
     
     
         38 . The electrocatalyst of  claim 24 , wherein the catalytic sites are on surfaces of the layers. 
     
     
         39 . The electrocatalyst of  claim 24 , wherein the electrocatalyst has an exchange current density ranging from about 2×10 −4  A/cm 2  to about 10×10 −4  A/cm 2 . 
     
     
         40 . The electrocatalyst of  claim 24 , wherein the electrocatalyst has a catalyst loading that ranges from about 10 μg/cm 2  to about 100 μg/cm 2 . 
     
     
         41 . The electrocatalyst of  claim 24 , wherein the electrocatalyst has a Tafel slope ranging from about of 25 mV/decade to about 100 mV/decade. 
     
     
         42 . The electrocatalyst of  claim 24 , wherein the electrocatalyst has a current density ranging from about of 5 mA/cm 2  to about 50 mA/cm 2 .