Enrichment of Polarized Alkynes over Negatively Charged Pt for Efficient Electrocatalytic Semihydrogenation

Abstract

Semihydrogenation of alkynes is a crucial industrial process for the mass production of polymer-grade alkenes and fine chemicals. An electrocatalytic semihydrogenation strategy presents a mild but powerful alternative to conventional processes under critical conditions and yet is suffering from a low catalytic efficiency due to the sacrificed intrinsic activity to depress unwanted overhydrogenation. Here, we report a negatively charged Pt (Pt δ− ) induced by coupling with strong electron donator W 2 C nanoparticles in dual-junction materials to promote the electrocatalytic semihydrogenation of alkynes to alkenes using water as the hydrogen source. The negatively charged surface of Pt metals enables the polarization and unexpected preferential enrichment of alkynes, accelerating the following semihydrogenation process on the real Pt δ− -based electrode. A significantly elevated energy barrier of overhydrogenation from the Pt δ− surface further ensures the semihydrogenation selectivity, breaking the selectivity-activity trade-off for semihydrogenation of a wide scope of alkynes. Moreover, the negatively charged Pt-based electrode as a reusable cathode could exhibit a turnover frequency of 310 h −1 at −0.4 V versus Ag/AgCl, surpassing 6-fold the reported semihydrogenation catalysts with potential advantages for practical applications.

Electron Divergence of Cuδ− and Pdδ+ in Cu3Pd Alloy-Based Heterojunctions Boosts Concerted C≡C Bond Binding and the Volmer Step for Alkynol Semihydrogenation

“…Electrocatalytic hydrogenation (ECH), employing water as a hydrogen proton source, emerges as a promising alternative method to conventional thermalcatalytic hydrogenation due to its inherent sustainability and atom economy. − Different from thermalcatalytic hydrogenation reliant on hydrogen molecule dissociation, electrocatalytic hydrogenation involves the active hydrogen species from the dissociation of water molecules on the tunable electrode surface environment, enabling easily continuous and amplified synthesis. − Pioneering works have shown the importance of the optimized composition of electrocatalysts and tunable interfacial structure to simultaneously promote selectivity and Faradaic efficiency (FE). − There is a consensus in the literature that a scaling relationship between the proton reduction step and the hydrogenation step limits the selective alkenol production at elevated working potentials or current densities, thereby leading to low energy efficiency for alkenol production and the consumption of excess amounts of electrocatalysts with relatively lower turnover frequencies (TOFs). It is highly alluring but very challenging to explore the bimetal centers with divergent catalytic activity to selectively facilitate the water splitting and follow the alkynol semihydrogenation steps without promoting the hydrogen evolution reaction (HER) process too much.…”