Metal-carbonate interface promoted activity of Ag/MgCO3 catalyst for aqueous-phase formaldehyde reforming into hydrogen.

[Display omitted] • Ag/MgCO 3 catalyst is constructed with stable Ag-carbonate interfaces on MgO support. • Ag/MgCO 3 exhibits superior low-temperature H 2 production activity in HCHO reforming than Ag/MgO. • O 2 -involved HCHO/H 2 O reforming pathway is proposed via active intermediates (i.e., O 2 −, OOH, H). • Facile activation of HCHO C H and H 2 O O H bonds contributes to high activity of Ag/MgCO 3. Aqueous-phase reforming of biomass-derived formaldehyde is one of efficient and sustainable routes to generate molecular hydrogen as clean energy resource. In this work, Ag/MgCO 3 catalyst is prepared with constructed stable carbonate-modified metal-support interfaces. Under mild and neutral reaction conditions, it exhibits a near an order of magnitude higher low-temperature activity in formaldehyde reforming reaction for producing hydrogen in comparison with Ag/MgO. The catalytic and spectral observations reveal that the Ag/MgCO 3 -catalyzed reaction follows an O 2 -involved HCHO/H 2 O reforming reaction pathway through O 2 −, OOH and H radicals as highly active intermediates. Ag/MgCO 3 catalyst shows high rates in isotopic H 2 -D 2 exchange and HCHO/D 2 O reforming reactions and displays an apparent activation energy (E a) as low as 7.5 kJ mol−1 within 10–50 °C, indicating facile activation of HCHO C H and H 2 O O H bonds. Furthermore, Ag/MgCO 3 catalyst adsorbs HCHO molecule in a favorable configuration and strength, as evidenced by the HCHO desorption profile. Comprehensive positive factors benefit to the superior hydrogen production activity of carbonate-modified Ag/MgCO 3 than Ag/MgO. [ABSTRACT FROM AUTHOR]