Continuous Atomic Hydrogen for Eminent Bromate Reduction via Palladium Coordination Manipulation

Palladium (Pd) hydrogenation reduction is a promising technique to remove bromate (BrO₃^–), an emerging contaminant frequently detected in an aqueous environment. However, continuous atomic hydrogen (H*) production remains a challenge because of weak Pd–support interactions and subsequent inactivation. In this study, the N-doped graphene-coordinated Pd could achieve an almost 100% BrO₃^– conversion rate during the continuous treatment of groundwater containing environmentally contaminated concentrations. The reduction performance experiments showed that N-doped graphene-coordinated Pd supported a higher turnover frequency value (12.4 min^–1) than most of the reported Pd-based catalysts. Thin sheets with defects and uniform N doping in graphene were able to induce the formation of Pd nanoparticles (Pd NPs) and Pd single atoms (Pd–N₄), respectively. In addition, doping N in graphene enables the catalyst to exhibit a higher catalytic activity. Quenching experiments and electron paramagnetic resonance tests further confirmed that the N-doped graphene-coordinated Pd had a high activity to produce more H* for BrO₃^– reduction. Therefore, the customized Pd coordination supported a highly effective continuous hydrogenation reduction of BrO₃^– in real groundwater treatment, making it a promising candidate for large-scale environmental applications.