Compared to nanostructured platinum (Pt) catalysts, ordered Pt-based intermetallic nanoparticles supported on a carbon substrate exhibit much enhanced catalytic performance, especially in fuel cell electrocatalysis. However, direct synthesis of homogeneous intermetallic alloy nanocatalysts on carbonaceous supports with high loading is still challenging. Herein, we report a novel synthetic strategy to directly produce highly dispersed MPt alloy nanoparticles (M = Fe, Co, or Ni) on various carbon supports with high catalyst loading. Importantly, a unique bimetallic compound, composed of [M­(bpy)3]2+ cation (bpy = 2,2′-bipyridine) and [PtCl6]2– anion, evenly decomposes on carbon surface and forms uniformly sized intermetallic nanoparticles with a nitrogen-doped carbon protection layer. The excellent oxygen reduction reaction (ORR) activity and stability of the representative reduced graphene oxide (rGO)-supported L10-FePt catalyst (37 wt %-FePt/rGO), exhibiting 18.8 times higher specific activity than commercial Pt/C catalyst without degradation over 20 000 cycles, well demonstrate the effectiveness of our synthetic approach toward uniformly alloyed nanoparticles with high homogeneity.

An urgent need in chemodynamic therapy (CDT) is to achieve high Fenton catalytic efficiency at small doses of CDT agents. However, simple general promotion of the Fenton reaction increases the risk of damaging normal cells along with the cancer cells. Therefore, a tailored strategy to selectively enhance the Fenton reactivity in tumors, for example, by taking advantage of the characteristics of the tumor microenvironment (TME), is in high demand. Herein, a heterogeneous CDT system based on copper−iron peroxide nanoparticles (CFp NPs) is designed for TME-mediated synergistic therapy. CFp NPs degrade under the mildly acidic conditions of TME, selfsupply H 2 O 2 , and the released Cu and Fe ions, with their larger portions at lower oxidation states, cooperatively facilitate hydroxyl radical production through a highly efficient catalytic loop to achieve an excellent tumor therapeutic efficacy. This is distinct from previous heterogeneous CDT systems in that the synergism is closely coupled with the Cu + -assisted conversion of Fe 3+ to Fe 2+ rather than their independent actions. As a result, almost complete ablation of tumors at a minimal treatment dose is demonstrated without the aid of any other therapeutic modality. Furthermore, CFp NPs generate O 2 during the catalysis and exhibit a TME-responsive T 1 magnetic resonance imaging contrast enhancement, which are useful for alleviating hypoxia and in vivo monitoring of tumors, respectively.

Noble metal-based multimetallic nanoparticles (NMMNs) have attracted great attention for their multifunctional and synergistic effects, which offer numerous catalytic applications. Combined experimental and theoretical studies have enabled formulation of various design principles for tuning the electrocatalytic performance through controlling size, composition, morphology, and crystal structure of the nanoparticles. Despite significant advancements in the field, the chemical synthesis of NMMNs with ideal characteristics for catalysis, including high activity, stability, product-selectivity, and scalability is still challenging. This review provides an overview on structure-based classification and the general synthesis of NMMN electrocatalysts. Furthermore, postsynthetic treatments, such as the removal of surfactants to optimize the activity, and utilization of NMMNs onto suitable support for practical electrocatalytic applications are highlighted. In the end, future direction and challenges associated with the electrocatalysis of NMMNs are covered.