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Production of hydrogen (H 2) from H 2 storage materials is very attractive as a source of sustainable energy. We report that AuNi@ZIF-8 alloys are very efficient nanocatalysts for H 2 evolution upon ammonia borane hydrolysis under visible-light illumination with turnover frequency 3.4 times higher than with the monometallic Ni catalyst in the dark. This improvement is attributed to dramatic volcano-type positive synergy optimized in Au 0.5 Ni 0.5 @ZIF-8, for which ZIF-8 is by far the superior support, as well as to the localized surface plasmon resonance induced between 450 and 620 nm. Infrared spectra analysis and tandem reaction confirm the origin of the hydrogen atoms, reveal the reaction mechanism, and suggest how the cleavage of the B–H and O–H bonds proceeds in this reaction. Deuteration experiments with D 2 O including primary kinetic isotope effects and density functional theory calculation under both dark and visible light conditions show that activation of H 2 O always is the rate-determining step. [Display omitted] • Gold alloys are optimized in ZIF-8 with nickel for very efficient nanocatalysis. • Dramatic synergy between Au and Ni in ZIF-8 for H 2 production catalysis. • ZIF-8 is a far superior support for nanocatalytic H 2 generation by gold nanoalloys. • NiAu@ZIF-8-catalyzed NH 3 BH 3 hydrolysis producing H 2 is boosted by visible light. • NH 3 BH 3 hydrolysis catal by NiAu@ZIF-8 with light produces 3 mol H 2 in 1min45s at rt. [ABSTRACT FROM AUTHOR]