The direct synthesis of hydrogen peroxide (H₂O₂) was studied by using a series of catalysts Pd/CNT-X (X = N, O) prepared by ethylene glycol reduction, which allows for better control of Pd nanoparticle size and catalyst hydrophilicity. The doping of both N and O into a carbon carrier could anchor Pd nanoparticles and enhance the hydrophilicity of catalysts, which would lead to significantly enhanced H₂O₂ productivity and stability compared to the original catalyst Pd/CNT. Detailed characterization indicated that this improvement was due to selective tuning of the Pd nanoparticle size, Pd⁰/Pd²⁺ ratio and catalyst hydrophilicity.