High‐Density Rare‐Earth Single‐Atom‐Triggered Unconventional Transition of Adsorption Configuration on La<sub>1</sub>Pd Monatomic Alloy Metallene for Sustainable Electrocatalytic Alkynol Semi‐Hydrogenation

Water splitting for hydrogen production is limited by high cell voltage and low energy conversion efficiencies due to the slow kinetic process of the oxygen evolution reaction (OER). Here, an electrolytic system is constructed in which the cathode and anode co‐release H2 at ultra‐low input voltage using formaldehyde oxidation reaction (FOR) instead of OER. The prepared RuCe co‐doped Cu2O nanotubes on copper foam (RuCe‐Cu2O/CF) are used as electrode materials for the HER‐FOR system. A current density of 0.8 A cm−2 is achieved at 0.55 V, and a stable hydrogen production process is realized at both the cathode and anode. Density functional theory (DFT) studies show that the synergistic effect of Ru and Ce drives: i) the d‐band center of RuCe‐Cu2O/CF away from the Fermi energy level; ii) the energy barrier for the C─H cracking of the H2C(OH)O* intermediate in FOR is lowered, which promotes the formation of H2 from H*, and iii) ΔGH* tends to 0 (−0.1 eV), optimizing the reaction kinetics of HER. This work provides a new design for an efficient catalyst for dual hydrogen production systems from water splitting.

Dual Hydrogen Production System: Synergistic Effect of Ru and Ce Over Cu₂O Nanotubes Drives Hydrogen Evolution and Formaldehyde Oxidation

Yu,

Zhang,

Jiang

et al. 2024

Proton Ionic Liquid Modulates Hydrogen Coverage and Subsurface Absorbed Hydrogen to Enhance Pd Metallene Electrocatalytic Semi‐hydrogenation of Alkynols

Yang,

Sun,

Mao

et al. 2024

Electrochemical semi‐hydrogenation of alkynols to produce high‐value alkenols is a green and sustainable approach. Although Pd can exhibit excellent semi‐hydrogenation properties, its intrinsic mechanism still lacks in‐depth study. Herein, a proton ionic liquid (PIL)‐modified Pd metallene (Pdene@PIL) is synthesized for the electrocatalytic semi‐hydrogenation of 2‐methyl‐3‐butyn‐2‐ol (MBY) to 2‐methyl‐3‐buten‐2‐ol (MBE). The PIL modification of Pdene@PIL resulted in an MBY conversion of 96.1% and MBE selectivity of 97.2%, respectively. Theoretical calculations indicate the electron transfer between Pdene and PIL, leading to easier adsorption of MBY on the Pd surface. The d‐band center of Pdene@PIL shifts away from the Fermi level, which weakens the adsorption of over‐hydrogenated intermediates. At the same time, the PIL modification facilitates the adsorption of surface‐adsorbed hydrogen (H*ads) and inhibits the formation of subsurface‐absorbed hydrogen (H*abs). In particular, the PIL modification optimizes Hads* coverage, reduces the reaction energy of the rate‐determining step (C5H8O*‐C5H9O*), and inhibits HER. The reduction of H*abs formation inhibits the transfer of Pd to PdHx and suppresses the over‐hydrogenation. This work provides new insights into the modulation of H* to enhance the alkynol electrocatalytic semi‐hydrogenation reaction (ESHR) process from the perspective of surface modification.

Trace Cu‐Induced Low C─N Coupling Barrier on Amorphous Co Metallene Boride for Boosting Electrochemical Urea Production

Wu,

Lin,

Mao

et al. 2024

The electrochemical C─N coupling of carbon dioxide (CO2) and nitrate(NO3‐) is an alternative strategy to the traditional high−energy industrial pathway for urea synthesis, which urgently requires the design of efficient catalysts to achieve high yield and Faraday efficiency (FE). Here, amorphous low‐content copper‐doped cobalt metallene boride (a‐Cu0.1CoBx metallene) is designed for urea synthesis via electrochemical C─N coupling. The a‐Cu0.1CoBx metallene can drive electrocatalytic C─N coupling of CO2 and NO3− for urea synthesis in CO2‐saturated 0.1 m KNO3 electrolyte, with 27.7% of FE and 312 µg h−1 mg−1cat. of yield at −0.5 V, as well as superior cycling stability. The in situ Fourier transform infrared and theoretical calculations reveal that electronic effect between Cu, Co, and B causes Cu and Co as dual active sites to promote the adsorption of reactants. Furthermore, the introduced trace Cu reduces the reaction energy barrier of the C─N coupling to facilitate urea synthesis. This work provides a promising route for the optimization of Co‐based metallene for the electrosynthesis of urea through C─N coupling.