Constructing dual active sites, adjusting electronic structures at interfaces and optimizing the adsorption energy of intermediates can effectively enhance water electrolysis performance. A novel Fe 3 C-Ru/NFs bifunctional catalyst is successfully synthesized via an electrospinning-carbonization method, in which sub-nanometer Ru particles coupled with Fe 3 C. Experimental results indicate that Fe 3 C-Ru/NFs catalyst delivers exceptional HER (18 mV@10 mA cm −2 , 202 mV@500 mA cm −2 ) and OER (263 mV@10 mA cm −2 , 382 mV@500 mA cm −2 ) performance in 1 M KOH solution. Moreover, Fe 3 C-Ru/NFs catalyst was employed as a bifunctional electrode in an overall water electrolyzer, resulting in a lower cell voltage and excellent stability (1.87 V, 150 h @ 500 mA cm −2 ). Density Functional Theory (DFT) calculation shows that the synergy between Ru and Fe sites can enhance electron transfer, and initiate a hydrogen spillover mechanism, and optimize intermediate adsorption energies, finally accelerating both HER and OER processes. This work offers valuable insights into developing low-cost, high-efficiency water electrolysis catalysts, demonstrating the significant potential for practical applications.
Liang Zhu,Yang Liu,Yanhui Gao,Ningxujin Ding,Danyu Wang,Liuliu Long,Beibei Wang,Junyu Lang,Evgeny I. Vovk,Yong Yang
The hydrogen dissociation and spillover mechanism on oxide-supported Cu catalysts play a pivotal role in the hydrogenation of carbon dioxide to methanol. This study investigates the hydrogen spillover mechanism on Cu/CeO2 catalysts using in situ spectral characterization under high-pressure reaction conditions and density functional theory (DFT) simulations. The research confirms that the Cu sites serve as the initial dissociation points for the hydrogen molecules. The chemically adsorbed hydrogen (H*) then spills over onto the CeO2 support and interacts with the lattice oxygen to form special hydroxyl groups, while simultaneously reducing the surrounding Ce4+ to form Ce3+. Interestingly, the temperature-programmed desorption (TPD) results found that heating the hydroxyl-containing surface mainly reverses H2 dissociation by desorbing H2 instead of forming H2O, while no significant vacancy formation was detected. The DFT calculation identified a subsurface pathway favoring hydrogen migration, which explained the dominating H2 in the TPD products. A chemical loop study after CO2/H2 cofeeding on the catalyst reveals that hydrogen spillover facilitates the highly reduced surface serving as the active centers, enabling a secondary methanol synthesis in a vacuum. This study provides a model of the formation and desorption pathways of hydrogen species on Cu/CeO2 catalysts and illustrates the key role of the hydrogen spillover mechanism in promoting the CO2 hydrogenation to methanol reaction through important experimental analysis.
Ru-based catalysts have shown great potential for the environmentally friendly industrialization of acetylene hydrochlorination. However, the high cost and reduction of active sites in Ru catalysts have limited their practical applications. In this study, we propose a strategy to optimize the electronic structure of Ru single-atom catalysts by leveraging the strong coordination ability of ligands with the metal and apply this strategy to acetylene hydrochlorination. The experimental results verify that the performance of the catalyst increases with the increase of the ligand. Characterization results indicate that ligands not only optimize the electronic properties of Ru single atoms by forming a RuCl 2 -N structure, but also enhance the adsorption of reactants on the catalysts. DFT calculations reveal that the ligand-modified Ru species can efficiently adsorb and activate acetylene molecules, while the adjacent excessive ligand can adsorb and dissociate HCl molecules. This ultimately leads to an addition reaction between acetylene and HCl through a hydrogen overflow mechanism.
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