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Currently, low intimacy between hydrogenation sites and acidic sites causes unsatisfactory catalytic activity and selectivity for the synthesis of 2,5-hexanedione from C 6 furan aldehydes (5-methylfurfural, 5-hydroxymethylfurfural). Herein, iodine(I) modification of Pd-supported catalysts (such as PdI/Al 2 O 3 and PdI/SiO 2 ) was investigated to modulate the hydrogenation sites and acidic sites. Unlike Pd catalysts that produced 71.4 % yield of 2-hydroxymethyl-5-methyl tetrahydrofuran via an overhydrogenation route of 5-methylfurfural, PdI catalysts showed a high efficiency for 2,5-hexanedione with 93.7 % yield by a hydrogenative ring-opening route. More importantly, the selective synthesis of 2,5-hexanedione from 5-hydroxymethylfurfural with a high yield of 50.2 % by the hydrogenolysis and subsequent ring-opening route was reported for the first time. I-modified Pd nanoparticles produced in-situ hydrogen spillover, which promoted the selective C=O hydrogenation and ring-opening steps by regulating the adsorption configuration of the reactants and the transformation of Lewis to Brønsted acidity, respectively., (© 2021 Wiley-VCH GmbH.)

Electroreduction of N 2 to NH 3 at ambient conditions using renewable electricity is promising, but developing efficient electrocatalysts is still challenging due to the inertness of N≡N bonds. Layer double hydroxides (LDHs) composed of first-row transition metals with empty d-orbitals are theoretically promising for N 2 electroreduction (NRR) but rarely reported. Herein, hollow NiCo-LDH nanocages with different Ni/Co ratios were prepared, and their electronic structures and atomic arrangements were critical. The synergetic mechanisms of Ni and Co ions were revealed, and the optimized catalytic sites were proposed. Besides, in-situ Raman spectroscopy and 15 N 2 isotopic labeling studies were applied to detect reaction intermediates and confirm the origin of NH 3 . As a result, high NH 3 yield of 52.8 μg h -1  mg cat -1 and faradaic efficiency of 11.5 % were obtained at -0.7 V, which are top-ranking among Co/Ni-based NRR electrocatalysts. This work elucidates the structure-activity relationship between LDHs and NRR and is instructive for rational design of LDH-based electrocatalysts., (© 2022 Wiley-VCH GmbH.)