While the surface charge state of co-catalysts plays a critical role for boosting photocatalysis,studies on surface charge regulation via their precise structure control remain extremely rare.Herein,metal-organic framework(MOF)stabilized bimetallic Pd@Pt nanoparticles,which feature adjustable Pt coordination environment and a controlled structure from core-shell to single-atom alloy(SAA),have been fabricated.Significantly,apart from the formation of a Mott-Schottky junction in a conventional way,we elucidate that Pt surface charge regulation can be alternatively achieved by changing its coordination environment and the structure of the Pd@Pt co-catalyst,where the charge between Pd and Pt is redistributed.As a result,the optimized Pd10@Pt1/MOF composite,which involves an unprecedented SAA co-catalyst,exhibits exceptionally high photocatalytic hydrogen production activity,far surpassing its corresponding counterparts.