Optimizing the metal-support interactions at the Pd-polymer carbon nitride Mott-Schottky heterojunction interface for...

We reported one novel strategy via band engineering of the semiconductor support to optimize the metal-support interactions at a Mott-Schottky heterojunction interface and enhance the metal's electrocatalytic hydrodechlorination (EHDC) performance. Taking palladium-polymer carbon nitride (Pd/PCN) as a model, the band tuning of PCN by heteroatomic phosphorus (P) doping substantially boosted the EHDC of 2,4-dichlorophenol (2,4-DCP, one typical chlorinated organic pollutants (COPs)) on Pd, and a peak specific activity of 0.172 min^-1 cm_Pd^-2 was achieved by Pd/P-PCN-0.25 (0.25 reflected the P content, and denoted the mass ratio of the P source to PCN precursor used in P-PCN synthesis), quadrupling 0.041 min^-1 cm_Pd^-2 of Pd/C and outperforming most of the reported catalysts. The mechanism study revealed the P doping in PCN enabled the positive shift of its Fermi level, which weakened the Pd-PCN interactions and alleviated the electron excess of Pd in Pd/PCN. The P-PCN in Pd/P-PCN-0.25 with the ideal band structure evoked a Pd electronic state that maximized EHDC efficiency. Further investigation into the intermediate products of EHDC on Pd/P-PCN and the biological safety of the 2,4-DCP-contaminated water after EHDC treatment demonstrated the EHDC over our catalyst was environmental-benignity for COPs abatement.