Proton exchange membrane fuel cells have been recently developed at an increasing pace as clean energy conversion devices for stationary and transport sector applications. High platinum cathode loadings contribute significantly to costs. This is why improved catalyst and support materials as well as catalyst layer design are critically needed. Recent advances in nanotechnologies and material sciences have led to the discoveries of several highly promising families of materials. These include platinum-based alloys with shape-selected nanostructures, platinum-group-metal-free catalysts such as metal-nitrogen-doped carbon materials and modification of the carbon support to control surface properties and ionomer/catalyst interactions. Furthermore, the development of advanced characterization techniques allows a deeper understanding of the catalyst evolution under different conditions. This review focuses on all these recent developments and it closes with a discussion of future research directions in the field.

Photodynamic therapy (PDT) is a promising therapeutic modality for cancer. However, current protocols using bare drugs suffer from several limitations that impede its beneficial clinical effects. Here, we introduce a new approach for an efficient PDT treatment. It involves conjugating a PDT agent, meso-tetrahydroxyphenylchlorin (mTHPC) photosensitizer, to gold nanoparticles (AuNPs) that serve as carriers for the drug. AuNPs have a number of characteristics that make them highly suitable to function as drug carriers: they are biocompatible, serve as biomarkers, and function as contrast agents in vitro and in vivo. We synthesized AuNPs and covalently conjugated the mTHPC drug molecules through a linker. The resultant functional complex, AuNP-mTHPC, is a stable, soluble compound. SH-SY5Y human neuroblastoma cells were incubated with the complex, showing possible administration of higher doses of drug when conjugated to the AuNPs. Then cells were irradiated with a laser beam at 650 nm to mimic the PDT procedure. Our study shows higher rates of cell death in cells incubated with the AuNP-mTHPC complex compared to the incubation with the free drug. Using the new complex may form the basis for a better PDT strategy for a wide range of cancers.

A variety of synthesis protocols for octahedral PtNi nanocatalysts have led to remarkable improvements in platinum mass and specific activities for the oxygen reduction reaction. Nevertheless, the values achieved are still only one tenth of the activity measured from Pt 3 Ni single-crystal (111) surfaces. These particles lose activity during potential cycling, primarily because of Ni leaching and subsequent loss of shape. Here, we present the syntheses and high catalytic oxygen reduction reaction activities of molybdenum-doped PtNi octahedral catalysts with different sizes (6−14 nm) and compositions. We show that the Mo-doped, Nirich, PtNi octahedral catalysts exhibit enhanced stability over their undoped counterpart. Scanning transmission electron microscopy with energy-dispersive Xray analysis reveals the particular elemental distribution for the size and composition of the different catalysts. By combining high-resolution compositional analysis with electrochemical measurements and online inductively coupled plasma mass spectrometry, it was possible to correlate the size, morphology, and composition with the oxygen reduction reaction activities before and after accelerated stress tests. The octahedral catalysts show high electrochemical surface areas and increasing specific activity with increasing surface area of the (111) facets and Ni content, leading to high mass activities. These results demonstrate the advantages of increasing the (111) surface area and Ni content of PtNi nano-octahedral catalysts to improve the performance and stability for the oxygen reduction reaction.

1 and − − 1.38 mA cm Pd 2 at 0.1 V versus reversible hydrogen electrode at 298 K. These are the highest values reported so far for an NiPd catalyst. By design, the synthetic approach is generic and can be applied to any pair of metals, either PGM or other transition metals, to synthesize alloyed or core-shell electrocatalysts.

Hollow particles of Pt-Ni-Au alloys have been prepared through a two-step reaction with the synthesis of NiPt octahedral and cuboctahedral templates followed by a galvanic replacement reaction by Au(iii). Metal etching presents an efficient method to yield hollow particles and investigate the Au diffusion in the metallic Pt-Ni framework through macroscopic (X-ray diffraction and SQUID magnetic measurement) and microscopic (HRTEM and STEM) measurements. The hollow particles retain the shape of the original nanocrystals. The nucleation of Au is found to be induced preferentially on the tip of the polyhedral nanocrystals while the etching of Ni starts from the facets leaving hollow octahedral particles consisting of 2 nm thick edges. In the presence of oleylamine, the Au tip grows and yields a heterogeneous dimer hollow-NiPt/Au. Without oleylamine, the Au nucleation is followed by Au diffusion in the Ni/Pt framework to yield a hollow single crystal Pt-Ni-Au alloy. The Pt-Ni-Au alloyed particles display a superparamagnetic behavior at room temperature.