Surfactant Directionally Assembled at the Electrode-Electrolyte Interface for Facilitating Electrocatalytic Aldehyde Hydrogenation.

Electrocatalytic hydrogenation of unsaturated aldehydes to unsaturated alcohols is a promising alternative to conventional thermal processes. Both the catalyst and electrolyte deeply impact the performance. Designing the electrode-electrolyte interface remains challenging due to its compositional and structural complexity. Here, we employ the electrocatalytic hydrogenation of 5-hydroxymethylfurfural (HMF) as a reaction model. The typical cationic surfactant, cetyltrimethylammonium bromide (CTAB), and its analogs are employed as electrolyte additives to tune the interfacial microenvironment, delivering high-efficiency hydrogenation of HMF and inhibition of the hydrogen evolution reaction (HER). The surfactants experience a conformational transformation from stochastic distribution to directional assembly under applied potential. This oriented arrangement hampers the transfer of water molecules to the interface and promotes the enrichment of reactants. In addition, near 100 % 2,5-bis(hydroxymethyl)furan (BHMF) selectivity is achieved, and the faradaic efficiency (FE) of the BHMF is improved from 61 % to 74 % at -100 mA cm-2. Notably, the microenvironmental modulation strategy applies to a range of electrocatalytic hydrogenation reactions involving aldehyde substrates. This work paves the way for engineering advanced electrode-electrolyte interfaces and boosting unsaturated alcohol electrosynthesis efficiency.

Cu Single-Atom Catalysts for High-Selectivity Electrocatalytic Acetylene Semihydrogenation.

The site isolation strategy has been employed in thermal catalytic acetylene semihydrogenation to inhibit overhydrogenation and C-C coupling. However, there is a dearth of analogous investigations in electrocatalytic systems. In this work, density functional theory (DFT) simulations demonstrate that isolated Cu metal sites have higher energy barriers on overhydrogenation and C-C coupling. Following this result, we develop Cu single-atom catalysts highly dispersed on nitrogen-doped carbon matrix, which exhibit high ethylene selectivity (>80 % Faradaic efficiency for ethylene, <1 % Faradaic efficiency for C4 , and no ethane) at high concentrations of acetylene. The superior performance observed in the electrocatalytic selective hydrogenation of acetylene can be attributed to the weak adsorption of ethylene intermediates and highly energy barriers on C-C coupling at isolated sites, as confirmed by both DFT calculations and experimental results. This study provides a comprehensive understanding of the isolated sites inhibiting the side reactions of electrocatalytic acetylene semihydrogenation.

Engineering the NiNC Catalyst Microenvironment Enabling CO2 Electroreduction with Nearly 100% CO Selectivity in Acid.

CO2 electrolysis in acid has emerged as a promising route to achieve high CO2 utilization due to the inhibition of undesired carbonate formation that generally occurs in alkaline or neutral conditions. However, the efficiency and stability of this system need to be further improved through tailoring of the electrocatalyst and its working environment. Here, a working microenvironment of structurally engineered NiNC catalyst for acidic CO2 electrolysis is probed and optimized by adding hydrophobic poly(tetrafluoroethylene) (PTFE) nanoparticles in the catalytic layer of gas-diffusion electrodes. The PTFE-modified electrode delivers nearly 100% CO Faradaic efficiency at an industry-relevant current density of 250 mA cm-2 , and a high single-pass CO2 utilization of 75.7% at a current density of 200 mA cm-2 under 20 sccm CO2 gas flow rate. Moreover, compared to a conventional electrode without added PTFE, the PTFE-modified electrode exhibits a substantially enhanced water-flooding-resistant ability. Mechanistic investigations reveal that a moderate PTFE modification can optimize the local CO2 /H2 O ratio in the catalytic layer, favoring the reduction of the diffusion layer thickness and the formation of a highly active and stable solid-liquid-gas interfacial microenvironment.