Role of the Cu-ZrO_(2) interface in the hydrogenation of levulinic acid to γ-valerolactone

Here we exquisitely fabricated Cu/ZrO_(2)-dp catalysts with plentiful Cu-ZrO_(2)interfaces by depositing amorphous ZrO_(2)onto Cu nanoparticles for the hydrogenation of levulinic acid(LA)to y-valerolactone(GVL).With the created plentiful CU-ZrO_(2)interfaces,the optimal catalyst 3 Cu/ZrO_(2)-dp exhibited exceptional catalytic performance under mild reaction conditions,and achieved the highest GVL mass productivity of 266.0 mmol GVL·h^(-1)·g^(-1)Cu,which was 12.5 and 2.3 times of CU/ZrO_(2)catalysts with equivalent Cu loadings prepared by traditional impregnation(3 Cu/ZrO_(2)-im)or co-precipitation(3 Cu/ZrO_(2)-cp).As far as we know,this GVL mass productivity stood at the highest level compared with those obtained using non-noble metal catalysts under similar reaction conditions.By systematic investigation with multiple characterizations,density functional theory(DFT)calculations,and kinetic studies,it was found that interfacial active centers were created at Cu-ZrO_(2)interfaces,which contained oxygen vacancies(O_(v)),negatively charged Cu^(δ)-and partially reduced Zr^(3+)The O_(v) favored the adsorption and activation of LA via its ketone group,while negatively charged Cu^(δ)-was able to enhance heterolysis of H2,which resulted in the formation of H^(+)-Cu^(δ)-and Zr^(3+)-H^(-)active species via hydrogen spillover.Also,plentiful acid sites,which derived from coordinatively unsaturated and defective Zr species,generated at Cu-ZrO_(2)interfaces.With the cooperation of interfacial active centers(Cu^(δ-)-O_(v)-Zr^(3+))and acid sites,the fabricated 3 Cu/ZrO_(2)-dp with plentiful Cu-ZrO_(2)interfaces achieved excellent catalytic performance for the hydrogenation of LA to GVL.Hence,the synergistic catalysis of Cu-ZrO_(2)interfaces provided an effective strategy for designing catalysts with a satisfactory performance for the hydrogenation of LA,which also can be expanded to other hydrodeoxygenation reactions.

A multi-step induced strategy to fabricate core-shell Pt-Ni alloy as symmetric electrocatalysts for overall water splitting

Devising an electrocatalyst with brilliant efficiency and satisfactory durability for hydrogen production is of considerable demand,especially for large-scale application.Herein,we adopt a multi-step consequential induced strategy to construct a bifunctional electrocatalyst for the overall water splitting.Graphene oxide(GO)was used as a carbon matrix and in situ oxygen source,which was supported by the octahedral PtNi alloy to form the PtxNiy-GO precursor.When calcinating in Ar atmosphere,the oxygen in GO induced the surface segregation of Ni from the PtNi octahedron to form a core-shell structure of Ptx@Niy.Then,the surface-enriched Ni continuously induced the reformation of C in reduced graphene oxide(rGO)to enhance the degree of graphitization.This multi-step induction formed a nanocatalyst Pt_(x)@Ni_(y)-rGO which has very high catalytic efficiency and stability.By optimizing the feeding ratio of PtNi(Pt:Ni=1:2),the electrolytic overall water splitting at 10 mA·cm^(-2) can be driven by an electrolytic voltage of as low as 1.485 V,and hydrogen evolution reaction(HER)only needs an overpotential of 37 mV in 1.0 M KOH aqueous solution.Additionally,the catalyst exhibited consistent existence form in both HER and oxygen evolution reaction(OER),which was verified by switching the anode and cathode of the cell in the electrolysis of water.This work provides a new idea for the synthesis and evaluation of the bifunctional catalysts for water splitting.