AbstractConstructing the efficacious and applicable bi-functional electrocatalysts and establishing out the mechanisms of organic electro-oxidation by replacing anodic oxygen evolution reaction (OER) are critical to the development of electrochemically-driven technologies for efficient hydrogen production and avoid CO₂ emission. Herein, the hetero-nanocrystals between monodispersed Pt (~ 2 nm) and Ni₃S₂ (~ 9.6 nm) are constructed as active electrocatalysts through interfacial electronic modulation, which exhibit superior bi-functional activities for methanol selective oxidation and H₂ generation. The experimental and theoretical studies reveal that the asymmetrical charge distribution at Pt–Ni₃S₂ could be modulated by the electronic interaction at the interface of dual-monodispersed heterojunctions, which thus promote the adsorption/desorption of the chemical intermediates at the interface. As a result, the selective conversion from CH₃OH to formate is accomplished at very low potentials (1.45 V) to attain 100 mA cm⁻² with high electronic utilization rate (~ 98%) and without CO₂ emission. Meanwhile, the Pt–Ni₃S₂ can simultaneously exhibit a broad potential window with outstanding stability and large current densities for hydrogen evolution reaction (HER) at the cathode. Further, the excellent bi-functional performance is also indicated in the coupled methanol oxidation reaction (MOR)//HER reactor by only requiring a cell voltage of 1.60 V to achieve a current density of 50 mA cm⁻² with good reusability.