Converting copper sulfide to copper with surface sulfur for electrocatalytic alkyne semi-hydrogenation with water

Abstract

Electrocatalytic alkyne semi-hydrogenation to alkenes with water as the hydrogen source using a low-cost noble-metal-free catalyst is highly desirable but challenging because of their over-hydrogenation to undesired alkanes. Here, we propose that an ideal catalyst should have the appropriate binding energy with active atomic hydrogen (H*) from water electrolysis and a weaker adsorption with an alkene, thus promoting alkyne semi-hydrogenation and avoiding over-hydrogenation. So, surface sulfur-doped and -adsorbed low-coordinated copper nanowire sponges are designedly synthesized via in situ electroreduction of copper sulfide and enable electrocatalytic alkyne semi-hydrogenation with over 99% selectivity using water as the hydrogen source, outperforming a copper counterpart without surface sulfur. Sulfur anion-hydrated cation (S2−-K+(H2O)n) networks between the surface adsorbed S2− and K+ in the KOH electrolyte boost the production of active H* from water electrolysis. And the trace doping of sulfur weakens the alkene adsorption, avoiding over-hydrogenation. Our catalyst also shows wide substrate scopes, up to 99% alkenes selectivity, good reducible groups compatibility, and easily synthesized deuterated alkenes, highlighting the promising potential of this method.

Stabilizing indium sulfide for CO2 electroreduction to formate at high rate by zinc incorporation

“…32 ) owing to the strong interaction between Zn and S (refs. 16 , 48 , 49 ), although it mainly produces H 2 (Supplementary Fig. 13 ).…”

Field-induced reagent concentration and sulfur adsorption enable efficient electrocatalytic semihydrogenation of alkynes

“…When tetramethylammonium hydroxide (TMAOH) and NaOH are used to replace KOH electrolytes, Pd@ArS-Pd 4 S NTs exhibit lower current density and a sluggish alkyne hydrogenation process under other identical conditions (fig. S14), due to the weaker interaction between S 2− and TMA + and the larger ionic hydration number and radius of the hydrated cation of Na + (H 2 O) n ( n = 7 for K + versus 13 for Na + ) ( 15 ). Consequently, the preliminary results suggest that both the NT structure and the concentrated K + are essential in promoting the electrochemical transfer semihydrogenation of alkynes with water, rationalizing our speculation and theoretical prediction.…”

“…Its Faraday efficiencies (FEs) of alkenes are highly dependent on the precise controls on cathodic potentials and reaction time. To address these issues, a low-coordinated copper cathode with surface sulfur (S) was then found that allowed the highly selective synthesis of alkenes across a wide potential range ( 15 ). However, its reaction rate was relatively low because of the weak hydrogenation ability of Cu itself, thus a higher potential is required to drive the semihydrogenation with only 3.6 to 10% FEs due to competitive hydrogen evolution reaction (HER).…”

Highly efficient ethylene production via electrocatalytic hydrogenation of acetylene under mild conditions

“…In contrast to the thermocatalytic path, this process is advantageous in being operatable under mild conditions and is environmental-friendly in combination with electroreduction of water based on renewable electricity, in which hydrogen is in-situ generated for the reduction reaction so that extra supply of H 2 can be avoided (Fig. 1 ), which emerges as an attractive route for semihydrogenation of alkynes 13 – 15 . By optimizing the Cu catalyst to expose more active facets, preferential adsorption and hydrogenation of acetylene is facilitated against hydrogen adsorption and evolution.…”