Nanocage-chain fuel cell catalysts: The expense and scarcity of platinum has driven efforts to improve oxygen-reduction catalysts in proton-exchange membrane fuel cells. Tian et al. synthesized chains of platinum-nickel alloy nanospheres connected by necking regions. These structures can be etched to form nanocages with platinum-rich surfaces that are highly active for oxygen reduction. In fuel cells running on air and hydrogen, these catalysts operated for at least 180 hours. Science , this issue p. 850

This review is aimed at introducing the remarkable progress made in the last three years in the development of base metal catalysts for hydrogenations and dehydrogenative transformations.

In this work, we compare the CO oxidation performance of Pt single atom catalysts (SACs) prepared via two methods: (1) conventional wet chemical synthesis (strong electrostatic adsorption–SEA) with calcination at 350 °C in air; and (2) high temperature vapor phase synthesis (atom trapping–AT) with calcination in air at 800 °C leading to ionic Pt being trapped on the CeO₂ in a thermally stable form. As-synthesized, both SACs are inactive for low temperature (<150 °C) CO oxidation. After treatment in CO at 275 °C, both catalysts show enhanced reactivity. Despite similar Pt metal particle size, the AT catalyst is significantly more active, with onset of CO oxidation near room temperature. A combination of near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and CO temperature-programmed reduction (CO-TPR) shows that the high reactivity at low temperatures can be related to the improved reducibility of lattice oxygen on the CeO₂ support.