Electrochemical method for enhancing electrocatalytic performance of metal deposition in unconventional-phase transition metal dichalcogenides

Abstract

The present invention relates to metallic nanostructures (e.g., Cu) on unconventional-phase TMDs, and an electrochemical method for the controlled growth of various Cu nanostructures, including single-atomically dispersed Cu (s-Cu), amorphous Cu (a-Cu) nanoclusters, and crystalline Cu (c-Cu) nanoparticles on 1T′ WS2 nanosheets. This method enhances the efficiency and selectivity of catalysts for the electrochemical upcycling of nitrate water into ammonia, achieving a Faradaic efficiency (FE) of at least 98% for ammonia at −0.8 V vs. RHE. Investigations reveal that the high performance arises from the synergistic cooperation between Cu sites and 1T′ WS2 supports, facilitating efficient hydrogenation and ammonia production. The Cu/1T′ TMDs nanostructures are versatile and can be applied in various catalytic fields.

What is claimed is: 
     
         1 . An electrochemical method for enhancing electrocatalytic performance of metal deposition in unconventional-phase transition metal dichalcogenides, comprising:
 preparing a working electrode comprising copper (Cu)-deposited unconventional-phase transition metal dichalcogenides nanostructures as a catalyst;   placing the working electrode in an electrochemical cell containing an aqueous electrolyte having nitrate ions; and   applying a potential ranging from −0.6 V to −1.0 V relative to a reference hydrogen electrode and conducting electrocatalytic reduction of nitrate in the aqueous electrolyte to reduce nitrate ions to ammonia,   
       wherein copper sites stabilize adsorbed nitrate intermediates, and wherein the copper-deposited unconventional-phase transition metal dichalcogenides nanostructures provide activated hydrogen species to promote surface hydrogenation, leading to the formation of ammonia. 
     
     
         2 . The method of  claim 1 , wherein the copper-deposited unconventional-phase transition metal dichalcogenides nanostructures are synthesized by the following steps:
 preparing one or more exfoliated transition metal dichalcogenides nanosheets via electrochemical exfoliation;   preparing an electrolyte solution of 0.1 M H 2 SO 4  comprising Cu salts of CuSO 4 ; and   performing an electrochemical deposition of Cu onto the one or more exfoliated transition metal dichalcogenides nanosheets to obtain the copper-deposited unconventional-phase transition metal dichalcogenides nanostructures, wherein the electrochemical deposition is conducted under an inert gas atmosphere.   
     
     
         3 . The method of  claim 2 , wherein the Cu is deposited in an amount ranging from 4 wt % to 12 wt %. 
     
     
         4 . The method of  claim 2 , wherein the electrochemical exfoliation involves an electrolyte solution containing tetraheptylammonium bromide dissolved in acetonitrile. 
     
     
         5 . The method of  claim 2 , wherein the one or more exfoliated transition metal dichalcogenides nanosheets are defect-free and exhibit electrophilic properties. 
     
     
         6 . The method of  claim 1 , wherein the unconventional-phase transition metal dichalcogenides nanostructures comprise 1T′ WS 2  nanosheet substrate, 1T′ MoS 2  nanosheet substrate, 1T′ MoSe 2  nanosheet substrate, or 1T′ WSe 2  nanosheet substrate. 
     
     
         7 . The method of  claim 6 , wherein the 1T′ WS 2  nanosheet substrate, 1T′ MoS 2  nanosheet substrate, 1T′ MoSe 2  nanosheet substrate, or 1T′ WSe 2  nanosheet substrate has a thickness ranging from 0.6 nm to 5 nm. 
     
     
         8 . The method of  claim 6 , further comprising controlling electrochemical deposition conditions to produce single-atomically dispersed Cu, amorphous Cu nanoclusters, or crystalline Cu nanoparticles on the 1T′ WS 2  nanosheet substrate, 1T′ MoS 2  nanosheet substrate, 1T′ MoSe 2  nanosheet substrate, or 1T′ WSe 2  nanosheet substrate. 
     
     
         9 . The method of  claim 8 , wherein the electrochemical deposition conditions comprise applied voltage, deposition time, electrolyte composition, and presence of ligands. 
     
     
         10 . The method of  claim 8 , wherein the single-atomically dispersed Cu is formed by applying an underpotential deposition (UPD) within a potential range of 0.1 V to 0.6 V. 
     
     
         11 . The method of  claim 8 , wherein the amorphous Cu nanoclusters is formed by applying a ligand-mediated deposition method within a potential range of −0.1 V to 0.6 V. 
     
     
         12 . The method of  claim 8 , wherein a hybrid material of the amorphous Cu nanoclusters on the 1T′ WS 2  nanosheet substrate achieves a Faradaic efficiency of at least 98% for ammonia production at −0.8 V relative to the reference hydrogen electrode. 
     
     
         13 . The method of  claim 1 , wherein the electrochemical deposition is carried out in a three-electrode configuration. 
     
     
         14 . The method of  claim 1 , further comprising recycling the catalyst at least 6 times without significant performance decay. 
     
     
         15 . The method of  claim 1 , further comprising determining produced ammonia concentration using an indophenol blue spectrophotometric method. 
     
     
         16 . The method of  claim 1 , wherein the aqueous electrolyte comprises 0.5 M K 2 SO 4  and 0.1 M KNO 3 . 
     
     
         17 . The method of  claim 16 , wherein the aqueous electrolyte further comprises penicillamine as a surfactant.