An effective cocatalyst is crucial for the high efficient visible photocatalytic hydrogen generation from formaldehyde. In this study, we develop a novel active Ag1Pd1 alloy cocatalyst with selective exposed (111) facet for the conversion toxic formaldehyde into hydrogen driven by visible light via modulation of the adsorption of HCHO, H2O molecules and H atom on optimized crystal facet of alloy cocatalyst. The Ag1Pd1(111)/RGO catalyst shows more than two times higher catalytic activity than Ag1Pd1 (100)/RGO catalyst under same condition. By taking advantage of the more efficient charge transfer and separation, the prolonged the lifetime of photogenerated electrons has been achieved over (111) facet AgPd alloy. Our result provides a new insight to develop the active cocatalyst by modulating crystal facet of alloy cocatalyst for hydrogen generation from formaldehyde under visible light irradiation. (C) 2019 Elsevier Inc. All rights reserved.