Studies of the electrocatalytic hydrodechlorination (EHDC) reaction using monodisperse AgPd nanoparticle (NP) model catalysts in the present work reveal the essential role of the catalytically inert Ag component in promoting bimetallic nanocatalyst's activity for the conversion of 2,4-dichlorophenol (2,4-DCP) to phenol (P). The EHDC reaction rate, current efficiency, and product selectivity were systematically investigated, leading to the observation of a volcano-type activity dependence on the Ag content in bimetallic NPs. The combination of kinetics analyses and density functional theory calculations demonstrates that the balance of 2,4-DCP adsorption and P desorption is the dominant factor for EHDC efficiency rather than other processes (e.g., hydrogen adsorbent formation). The presence of Ag, if precisely controlled in the proper range, alleviates the overstrong adsorption of P, allowing for a much enhanced EHDC kinetics compared to single-component Pd. This work provides a deep understanding of the EHDC mechanism over bimetallic nanocatalysts and a facile approach to optimizing this important environmental electrocatalysis strategy.

A novel coumarin-based fluorescent probe, P-CM, for quantitative detection of nitroxyl (HNO) was developed. P-CM exhibits a selective response to HNO over other biological reductants and was also applied for quantitative detection of HNO in bovine serum with satisfactory results.

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We present an enhanced catalytic efficiency of palladium (Pd) nanoparticles (NPs) for the electrocatalytic hydrodechlorination (EHDC) reaction by incorporating the tetraethylammonium chloride (TEAC) ligand into the surface of NPs. Both experimental and theoretical analyses reveal that the surface-adsorbed TEAC is converted to molecular amine (primarily triethylamine) under reductive potentials, forming a strong ligand–Pd interaction that is beneficial to the EHDC kinetics. Using the EHDC of 2,4-dichlorophenol (2,4-DCP), a dominant persistent pollutant identified by the U.S. Environmental Protection Agency, as an example, the Pd/amine composite delivers a mass activity of 2.32 min–1 gPd –1 and a specific activity of 0.16 min–1 cm–2 at −0.75 V versus Ag/AgCl, outperforming Pd and most of the previously reported catalysts. The mechanistic study reveals that the amine ligand offers three functions: the H+-pumping effect, the electronic effect, and the steric effect, providing a favorable environment for the generation of reactive hydrogen radicals (H*) for hydrogenolysis of the C–Cl bond. It also weakens the adsorption strength of EHDC products, alleviating their poisoning on Pd. Investigation into the intermediate products of EHDC on Pd/amine and the biological safety of the 2,4-DCP-contaminated water after EHDC treatment demonstrates that EHDC on Pd/amine is environmentally benign for halogenated organic pollutant abatement. This work suggests that the tuning of NP catalysis using facile ligand post-treatment may lead to new strategies to improve EHDC for environmental remediation applications.