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Platinum (Pt)–group metals, which are scarce and expensive, are used for the demanding oxygen reduction reaction (ORR) in hydrogen fuel cells. One competing approach for reducing their use is to create nanoparticles with earth-abundant metals to increase their activity and surface area; another is to replace them with metals such as cobalt (Co) in carbide or nitride sites. Chong et al. thermally activated a Co metal-organic framework compound to create ORR-active Co sites and then grew PtCo alloy nanoparticles on this substrate. The resulting catalyst had high activity and durability, despite its relatively low Pt content. Science , this issue p. 1276 Active cobalt sites and platinum-cobalt nanoparticles are combined in a highly active and durable oxygen reduction catalyst. Achieving high catalytic performance with the lowest possible amount of platinum is critical for fuel cell cost reduction. Here we describe a method of preparing highly active yet stable electrocatalysts containing ultralow-loading platinum content by using cobalt or bimetallic cobalt and zinc zeolitic imidazolate frameworks as precursors. Synergistic catalysis between strained platinum-cobalt core-shell nanoparticles over a platinum-group metal (PGM)–free catalytic substrate led to excellent fuel cell performance under 1 atmosphere of O 2 or air at both high-voltage and high-current domains. Two catalysts achieved oxygen reduction reaction (ORR) mass activities of 1.08 amperes per milligram of platinum (A mg Pt −1 ) and 1.77 A mg Pt −1 and retained 64% and 15% of initial values after 30,000 voltage cycles in a fuel cell. Computational modeling reveals that the interaction between platinum-cobalt nanoparticles and PGM-free sites improves ORR activity and durability.

For the large-scale sustainable implementation of polymer electrolyte membrane fuel cells in vehicles, high-performance electrocatalysts with low platinum consumption are desirable for use as cathode material during the oxygen reduction reaction in fuel cells. Here we report a carbon black-supported cost-effective, efficient and durable platinum single-atom electrocatalyst with carbon monoxide/methanol tolerance for the cathodic oxygen reduction reaction. The acidic single-cell with such a catalyst as cathode delivers high performance, with power density up to 680 mW cm −2 at 80 °C with a low platinum loading of 0.09 mg Pt cm −2 , corresponding to a platinum utilization of 0.13 g Pt kW −1 in the fuel cell. Good fuel cell durability is also observed. Theoretical calculations reveal that the main effective sites on such platinum single-atom electrocatalysts are single-pyridinic-nitrogen-atom-anchored single-platinum-atom centres, which are tolerant to carbon monoxide/methanol, but highly active for the oxygen reduction reaction. High-performance electrocatalysts for the oxygen reduction reaction (ORR) typically use platinum (Pt), however its high cost is a hindrance to commercial scale up. Here, the authors report a cost-effective, efficient and durable Pt single-atom electrocatalyst for ORR with a Pt utilization of 0.13 g Pt kW −1 in a fuel cell.

Little is known about the demographics of people who use cannabis, including how use trends within population subgroups have evolved over time. It is therefore challenging to know if the demographics of participants enrolled in cannabis clinical trials are representative of those who use cannabis. To fill this knowledge gap, data from the National Survey on Drug Use and Health (NSDUH) on “past-month” cannabis use across various population subgroups in the United States was examined from 2002 to 2021. The most notable increases in “past-month” cannabis use prevalence occurred in those aged 65 and older (2,066.1%) and 50–64-year-olds (472.4%). In 2021, people reporting “past-month” cannabis use were 56.6% male and 43.4% female. Distribution across self-reported race and ethnicity was 64.1% White, 14.3% Black, 14.1% Hispanic, and 3.1% more than one race. And many ages were represented as 24.4% were 26–34, 24.1% were 35–49, 22.4% were 18–25, and 17.6% were 50–64 years old. To understand if these population subgroups are represented in cannabis clinical trials, participant demographics were extracted from peer-reviewed clinical trials reporting on pharmacokinetic and/or pharmacodynamic models of cannabis or cannabinoids. Literature was grouped by publication year (2000–2014 and 2015–2022) and participant prior exposure to cannabis. Results identified that cannabis clinical trial participants are skewed toward overrepresentation by White males in their 20s and 30s. This represents structural discrimination in the research landscape that perpetuates social and health inequities.

Nature Communications 8: Article number: 15938 (2017); Published: 24 July 2017; Updated: 27 September 2017. The affiliation details for one of the corresponding authors, Ying Wang, are incorrect in this Article. This author is incorrectly affiliated with ‘University of Chinese Academy of Sciences, Beijing 100049, China.

Finding inexpensive alternatives to platinum group metals (PGMs) is essential for reducing the cost of proton exchange membrane fuel cells (PEMFCs). Numerous materials have been investigated as potential replacements of Pt, of which the transition metal and nitrogen-doped carbon composites (TM/Nx/C) prepared from iron doped zeolitic imidazolate frameworks (ZIFs) are among the most active ones in catalyzing the oxygen reduction reaction based on recent studies. In this report, we demonstrate that the catalytic activity of ZIF-based TM/Nx/C composites can be substantially improved through optimization of synthesis and post-treatment processing conditions. Ultimately, oxygen reduction reaction (ORR) electrocatalytic activity must be demonstrated in membrane-electrode assemblies (MEAs) of fuel cells. The process of preparing MEAs using ZIF-based non-PGM electrocatalysts involves many additional factors which may influence the overall catalytic activity at the fuel cell level. Evaluation of parameters such as catalyst loading and perfluorosulfonic acid ionomer to catalyst ratio were optimized. Our overall efforts to optimize both the catalyst and MEA construction process have yielded impressive ORR activity when tested in a fuel cell system.

Achieving high catalytic performance with the lowest possible amount of platinum is critical for fuel cell cost reduction. In this paper, we describe a method of preparing highly active yet stable electrocatalysts containing ultralow-loading platinum content by using cobalt or bimetallic cobalt and zinc zeolitic imidazolate frameworks as precursors. Synergistic catalysis between strained platinum-cobalt core-shell nanoparticles over a platinum-group metal (PGM)–free catalytic substrate led to excellent fuel cell performance under 1 atmosphere of O2or air at both high-voltage and high-current domains. Two catalysts achieved oxygen reduction reaction (ORR) mass activities of 1.08 amperes per milligram of platinum (A mgPt-1) and 1.77 A mgPt-1and retained 64% and 15% of initial values after 30,000 voltage cycles in a fuel cell. Lastly, computational modeling reveals that the interaction between platinum-cobalt nanoparticles and PGM-free sites improves ORR activity and durability.