Disclosing the active integration structure and robustness of a pseudo-tri-component electrocatalyst toward alkaline hydrogen evolution

Designing multicomponent integration catalysts(MICs)has been a promising strategy for improving electrocatalytic hydrogen evolution reaction(HER)due to the highly active interfaces as well as electronic synergy.Nevertheless,many fundamental questions such as their actual active species and the influence on long-term stability remain to be answered.Herein,we present the structural evolution from a pseudotri-component electrocatalyst of nitrogen-doped carbon supported nickel/vanadium nitride/vanadium oxide(Ni-VN-V_(2)O_(3)/NC)nanorods to the heterostructural nickel/vanadium nitride(Ni-VN/NC)nanosheets during chemical or electrochemical processes.The self-reconstructed Ni-VN/NC exhibits a robust stability under alkaline conditions,while maintaining initial efficient HER activity with a low overpotential of 76 mV at the current density of 10 mA cm^(-2).Theoretical calculations and quasi-in-situ spectroscopic technology unveil the redistribution of electrons on the synergistic active interface,which synchronously optimizes the affinities for hydrogen,hydroxide,and water molecules,thereby remarkably accelerating the HER kinetics by reducing the barrier of Volmer step.

Cu2O-Au Nanocomposites with Novel Structures and Remarkable Chemisorption Capacity and Photocatalytic Activity

The decomposition of Cull nanoparticles in aqueous solution has been successfully developed as a novel method for the preparation of Cu2O nanoparticles. In particular, we found that the decomposition of Cull nanoparticles in aqueous solution could be catalyzed by Au colloids, forming CU2O-Au nanocomposites. The composition and structure of the resulting Cu2O-Au nanocomposites have been characterized in detail by inductively coupled plasma atomic emission spectroscopy, powder X-ray diffraction, N2 adsorption-desorption isotherms, infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. Their visible-light-driven photocatalytic activity toward various dye molecules has also been investigated. Depending on the Au：Cu ratio, Cu20-Au nanocomposites exhibit different novel nanostructures including a beautiful flower-like nanostructure that consists of polycrystalline Cu2O, amorphous Cu2O and Au colloids. We propose that the rapidly-generated bubbles of H2 during the course of the catalytic decomposition reaction drive the simultaneously-formed Cu2O to form amorphous curved thin foils and might also act as a template to assemble curved thin foils of amorphous Cu2O, polycrystalline Cu2O and Au colloids into uniform nanostructures. A Cu2O-Au nanocomposite with a Cu：Au ratio of 40 exhibits remarkable chemisorption capacity and visible-light-driven photocatalytic activity towards methyl orange and acid orange 7 and is a promising chemisorption-photocatalysis integrated catalyst. The catalytic decomposition of the metal hydride might open up a new approach for the fabrication of other metal/metal oxide nanocomposites with novel nanostructures and properties.

Application of MnCeO_(x)supported on palygorskite and Al(OH)_(3)for HCHO oxidation:Catalytic performance and stability

Indoor formaldehyde(HCHO)is an important air pollutant,while it is very difficult to reduce HCHO to low-level(e.g.<0.08 mg/m^(3)).Catalytic oxidation at ambient temperature has been increasingly recognized as one of the important methods to mitigate HCHO pollution due to its good effectiveness,stability,and recyclability.To further improve the activity of catalytic oxidation,this study develops the integrated MnCeO_(x)catalysts supported on palygorskite(Pal)and aluminium hydroxide(Al(OH)_(3)).Our results indicate that the synergistic interaction in MnCeO_(x)through the oxygen transfer mechanism from the oxygen reservoir CeO_(2)to MnOxsignificantly improves the activity.Pal,Al(OH)_(3),etc.were applied as the supports with a focus on their dispersion,microstructure,strength,and relative role.MnCeO_(x)can be anchored on the surface of Al(OH)_(3)with high dispersion.With the integrated catalyst,HCHO concentration decreases from 1.012 to 0.086 mg/m^(3)within 48 h.Higher oxidation activity of MnCeO_(x)powder may be ascribed to the amount of active components on the surface.The incorporation of ZSM-5 and activated carbon can improve the adsorption of HCHO,and all integrated catalysts exhibit stronger activities,with HCHO being degraded to the level lower than 0.08 mg/m^(3).Meantime,the samples exhibit good stability and strength(20.2 MPa)without obvious decrease over five consecutive stability experiments.