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.

We report a generalized wet-chemical methodology for the synthesis of transition-metal (M)-doped brookite-phase TiO2 nanorods (NRs) with unprecedented wide-range tunability in dopant composition (M = V, Cr, Mn, Fe, Co, Ni, Cu, Mo, etc.). These quadrangular NRs can selectively expose {210} surface facets, which is induced by their strong affinity for oleyl­amine stabilizer. This structure is well preserved with variable dopant compositions and concentrations, leading to a diverse library of TiO2 NRs wherein the dopants in single-atom form are homogeneously distributed in a brookite-phase solid lattice. This synthetic method allows tuning of dopant-dependent properties of TiO2 nanomaterials for new opportunities in catalysis applications.

Generalized synthetic strategies for nanostructures with well-defined physical dimensions and broad-range chemical compositions are at the frontier of advanced nanomaterials design, functionalization, and application. Here, we report a composition-programmable synthesis of multimetallic phosphide CoMP x nanorods (NRs) wherein M can be controlled to be Fe, Ni, Mn, Cu, and their binary combinations. Forming Co2P/MP x core/shell NRs and subsequently converting them into CoMP x solid-solution NRs through thermal post-treatment are essential to overcome the obstacle of morphology/structure inconsistency faced in conventional synthesis of CoMP x with the different M compositions. The resultant CoMP x with uniform one-dimensional (1-D) structure provides us a platform to unambiguously screen the M synergistic effects in improving the electrocatalytic activity, as exemplified by the oxygen evolution reaction. This new approach mediated by core/shell nanostructure formation and conversion can be extended to other multicomponent nanocrystal systems (metal alloy, mixed oxide, and chalcogenide, etc.) for diverse applications.

Nanostructures with nonprecious metal cores and Pt ultrathin shells are recognized as promising catalysts for oxygen reduction reaction (ORR) to enhance Pt efficiency through core/shell interfacial strain and ligand effects. However, core/shell interaction within a real catalyst is complex and due to the presence of various interfaces in all three dimensions is often oversimply interpreted. Using Co2P/Pt core/shell structure as a model catalyst, we demonstrate, through density functional theory (DFT) calculations that forming Co2P­(001)/Pt­(111) interface can greatly improve Pt energetics for ORR, while Co2P­(010)/Pt­(111) is highly detrimental to ORR catalysis. We develop a seed-mediated approach to core/shell Co2P/Pt nanorods (NRs) within which Co2P­(001)/Pt­(111) interface is selectively expressed over the side facets and the undesired Co2P­(010)/Pt­(111) interface is minimized. The resultant Co2P/Pt NRs are highly efficient in catalyzing ORR in acid, superior to benchmark CoPt alloy and Pt nanoparticle catalyst. As the first example of one-dimensional (1D) core/shell nanostructure with an ultrathin Pt shell and a nonprecious element core, this strategy could be generalized to develop ultralow-loading precious-metal catalysts with favorable core/shell interactions for ORR and beyond.

By balancing bimetallic composition-associated ligand and ensemble effects, Ag₁₅Pd₈₅ nanoparticles show enhanced catalytic properties for electrochemical CO₂ reduction.