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Upgrading of the biomass-derived levulinic acid (LA) with the activation of carbonyl functional groups is a pivotal reaction in converting biomass into high-value-added products. Herein, we reported a modified strategy to synthesize highly dispersed noble-metal-free bimetallic NiCu alloy nanoparticles (NPs) from metal−organic frameworks for the selective hydrogenation of LA, in which the ligand effect between Ni and Cu plays a crucial role under relatively mild conditions. Among the tested catalysts, the catalyst with a Ni/Cu ratio of 1:2 presented the best catalytic performance in comparison with the homometallic Ni/Cu and bimetallic catalysts with different ratios; an outstanding yield of 93.9% was obtained for γ-valerolactone (GVL). Both experimental studies and characterization analyses verified that the ligand effect is responsible for the excellent catalytic performance. A possible reaction pathway for the samples in the LA hydrogenation process is proposed; after dissociation of adsorbed H 2 on the NiCu alloy surface, reactant LA is adsorbed and activated by NPs with the formation of intermediate, and through a self-condensation reaction to form products. The straightforward synthesis, superior performance, and high stability make these noble-metal-free bimetallic NiCu nanoparticles very attractive for the transformation of various biomass-derived sources into valuable products.

Nickel-based layered double hydroxides (LDHs) are promising electrode materials in the fields of energy storage (supercapacitors) and conversion (urea oxidation). The rational construction of atomic and electronic structure is crucial for nickel-based LDHs to realize their satisfactory electrochemical performance. Herein, we report a facile, ecofriendly, one-step synthesis process to construct petal-like oxygen-deficient NiAl-LDH nanosheets for hybrid supercapacitors (HSCs) and urea oxidation reaction (UOR). The asprepared NiAl-LDH nanosheets with rich oxygen vacancies possess a large specific surface area of 216.6 m 2 g -1 and a desirable electronic conductivity of 3.45 × 10 -4 S cm -1 to deliver an ultra-high specific capacitance of 2801 F g -1 (700 C g -1 ) at 1 A g -1 . Furthermore, high specific energy of 50.0 W h kg -1 at 400 W kg -1 and excellent cycle stability with 91% capacitance retention after 10,000 cycles are achieved by the NiAl-LDHs/ CFP (carbon fiber paper) (+)//YP-80F (a commercial activated carbon) (-) HSC. Besides, NiAl-LDH nanosheets also work as an efficient electrocatalyst for UOR, which only requires 1.42 V vs. reversible hydrogen electrode to drive 10 mA cm -2 in 1 mol L −1 KOH with 0.33 mol L −1 urea. This remarkable performance is superior to most reported values of previous candidates owing to the thin structure of NiAl-LDH nanosheets for exposing more active sites and abundant oxygen vacancies. In addition, various reaction parameters are investigated to optimize the electrochemical performance. In general, this work paves a new way for the architecture of multifunctional nanostructured energy materials.

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