Ligand-modified palladium nanoparticles deposited on ac arbon carrier efficiently catalyze the direct synthesis of H 2 O 2 and the unique performance is due to their hybrid nanostructure.Catalytic testing demonstrated that the selectivity increases with the HHDMA ligand content from 10 %f or naked nanoparticles up to 80 %, rivalling that obtained with state-of-the-art bimetallic catalysts (HHDMA = C 20 H 46 NO 5 P). Furthermore,i tr emains stable over five consecutive reaction runs owingt ot he high resistance towards leaching of the organic moiety,arising from its bond with the metal surface.As rationalized by density functional theory,t his behavior is attributed to the adsorption mode of the reaction intermediates on the metal surface.Whereas they lie flat in the absence of the organic shell, their electrostatic interaction with the ligand result in aunique vertical configuration which prevents further dissociation and over-hydrogenation. These findings demonstrate the importance of understanding substrate-ligand interactions in capped nanoparticles to develop smart catalysts for the sustainable manufacture of hydrogen peroxide.Hydrogen peroxide,H 2 O 2 ,a ttracts growing attention as ag reen alternative to traditional stoichiometric oxidants in awide range of applications within the textile,pulp bleaching, waste water treatment, metallurgy,c osmetic,a nd pharmaceutical industries.Owing to the advantages of its use,that is, the high atom economy and the generation of water as the only byproduct, [1] an increase of its global market value from 3.7 to 6.0 billion USD between 2014 and 2023 is forecasted. [2] Nowadays,t he production of H 2 O 2 relies exclusively on the anthraquinone process,which, despite being safe and suitable for continuous operation, involves the use of quinones and solvents resulting in energy-intensive purification steps and the generation of high amounts of waste,t hus being competitive only at large scale. [1,3] Thedirect synthesis of H 2 O 2 is an appealing alternative that has the potential to be exploited in decentralized plants at any scale due to the 1) absence of organic substrates,2 )use of green solvents such as water or methanol, and 3) simplified purification. [1,4] Its applicability has been widely investigated as such or in tandem with selective oxidation reactions using heterogeneous or, seldom, homogeneous catalysts. [5] Albeit the number of advantages over the traditional route,i ts industrial implementation has been hindered by the limited selectivity of the most active catalyst identified, that is,s upported Pd nanoparticles (NPs). [6] Indeed, besides facilitating the reaction between molecularly adsorbed O 2 and Ha toms,P dN Ps favor O 2 dissociation leading to undesired water formation (Scheme 1). [7] To overcome this limitation, the addition of asecond metal, chiefly Au or Sn, which was shown to generate active sites that prevent O À Ob ond cleavage,r esulted in the most selective catalysts reported to date. [8] Still, the added loading of costly and/or toxic metals h...