Johnson Matthey Technology Review - Fast Track

The dynamics of nanofluids on rotating disks is significantly relevant in microscale and industrial transport processes, especially when integrated with non-Newtonian and microstructural influences. In view of this, the current work examines the flow of micropolar nanofluid across an off-centered rotating disk, including the effects of quadratic thermal radiation and convective heat transfer.  The effect of the nanoparticles’ morphological features, particularly their shape and aspect ratio, as well as the role of the nanolayer thermal conductivity at the solid-liquid interface, are also studied to evaluate how they affect the nanofluid’s effective transport capabilities. Further, the Runge-Kutta Fehlberg’s fourth-fifth order scheme is employed to numerically solve the reduced equations. Moreover, the Taguchi approach is utilized to study the heat transportation rate. The significance of various parameters on the fluid profiles is illustrated graphically. The results show that non-spherical nanoparticles diminish the thermal efficiency more than brick and cylindrical particles. Increasing the radiation parameter and the Biot number enhances the thermal profile. Taguchi analysis shows that the temperature ratio has more influence on the Nusselt number (59.33%), whereas the magnetic parameter has the least impact (4.30%). This comprehensive approach has the potential to significantly enhance the design of thermal management systems, rotating machinery, and microfluid applications that increase heat transmission.

Catalyst layers, with commercial PtNi/TKK (TECNiE52; platinum 46.5 wt%), PtCo/TKK (TEC36E52; platinum 45.8 wt%) catalysts, and an in-house catalyst PtNi-NC (platinum 38.4 wt%), synthesised using acoustic mixer and a tube furnace, are prepared using three different ionomers: 20 wt% Nafion®, 60 wt% polytetrafluoroethylene (PTFE), and an in-house 5 wt% ionomer (‘Ionomer X’). These inks are bar-coated onto carbon paper gas diffusion layers (GDLs), which are cut into 3 cm × 5 cm pieces. The coated layers are tested for oxygen reduction in a commercial gas diffusion electrode (GDE) test cell, FlexCell® (Gaskatel GmbH, Germany), using 85 wt% phosphoric acid at both room temperature and at 155°C. This study evaluates the polynorbornene (PNB)-based in-house ionomer performance as binder and in-house catalyst oxygen reduction reaction (ORR) activity in comparison to commercial products. The catalyst layers are characterised using X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS), and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Among the catalyst layers prepared with PTFE ionomer and tested at 155°C, the in-house catalyst demonstrates the highest ORR activity. Ionomer X proves to be a good candidate to be used as a per- and polyfluoroalkyl-free binder for high-temperature (HT) proton exchange membrane fuel cell (PEMFC) applications.

Microplastics (MPs), a class of emerging pollutants, are widely present in the atmosphere. The present study was conducted with the objective of investigating the distribution of microplastics in the traffic environment. To this end, a year-long sampling programme was implemented on Lianhua Street in Zhengzhou, China. This street is a typical urban arterial road characterised by a high daily traffic volume and a mixture of commercial and residential surroundings. The samples were first analyzed for quantity and shape by stereomicroscopy, followed by polymer identification via micro-Raman spectroscopy (532 nm laser). The findings indicated that the average concentration of MPs in traffic areas was highest in winter (2340 ± 660 items/m3), followed by autumn and summer, and lowest in spring (960 ± 480 items/m3). Concentrations were greater on non-working days compared to working days, but there was no significant difference between peak and off-peak traffic hours. Most traffic-related MPs detected between 10 and 30 µm (69.2%). The average particle size was largest in summer (27.77 ± 16.53 µm), then autumn (26.75 ± 16.50 µm), spring (26.25 ± 13.74 µm), and smallest in winter (21.14 ± 11.18 µm). The main polymer types identified were tire wear particles (TWPs), ethylene-vinyl acetate (EVA), polyethylene (PE), and polyurethane (PU), accounting for 79.7%, 14.5%, 5.1%, and 0.7% of the annual average, respectively. TWPs and PE were most prevalent in spring, while TWPs and EVA dominated during the other seasons. Microplastics primarily appeared as granules (76.6%), fragments (20.2%), and fibers (3.2%). The findings reveal the temporal distribution of MPs in traffic environments and provide essential baseline data for their management and regulation.

Fuel cells for heavy-duty applications have garnered significant attention. Decades of advancements in stable oxygen reduction reaction (ORR) catalysts must now be leveraged to meet the increased cyclability demands of the heavy-duty vehicle market. The deposition of metal oxide coatings on Pt-based catalysts for ORR is hypothesized to balance high initial surface area with short-term electrochemical surface area (ECSA) retention in acid electrolytes. To explore this potential, a literature review covering 2001–2023 was conducted. Between-study heterogeneity was assessed through regression analyses at a 5% significance level. A total of 24 studies evaluated the electrochemical properties of metal oxide-coated Pt-based catalysts. Regression analyses indicated that 4-9 wt.% TiO2-coated catalysts on thin-film rotating disk electrodes degrade in a systematic manner, making their properties more predictable. In contrast, 11-55 wt.% SiO2-coated catalysts exhibited higher active surface area retention in comparison to TiO2-coated catalysts but with less consistency. Our findings suggest that thinner, atomically-grown MO2-type metal oxide coatings with more ionic M–O bonds, such as TiO2, provide the optimal balance between active site accessibility and catalyst stability under potential cycling. Furthermore, metal oxide coating shows potential for protecting and stabilizing platinum particles against dissolution and coalescence, presenting a promising avenue for further research to optimize ORR activity and long-term performance.

This study presents the design and scaling of a pilot-scale process for synthesizing antimicrobial oxygenated apatites, with emphasis on reproducibility and industrial scalability. The system achieves a daily production of 600 g of bioactive apatite using calcium nitrate or chloride, and 300 g/day with calcium carbonate under optimized conditions. Key units—including a double-jacketed reactor (40°C) with a marine agitator and an optimized mixer—were dimensioned using experimental data to maintain a Ca/P ratio of 1.575, ensuring structural integrity and controlled release of oxygenated species. Heat transfer, mixing dynamics, and agitation power were rigorously calculated to enable consistent scale-up. This work provides a validated framework for transitioning lab-scale apatite synthesis to controlled industrial production.

Single-atom catalysts (SACs) and single-atom alloy (SAA) catalysts are emerging as promising catalysts that allow maximising atom efficiency whilst improving catalyst performance. This literature review focusses on the evaluation of SACs and SAAs for thermocatalytic CO2 methanation, providing mechanistic insights into CO2 methanation on SACs and SAAs. The key findings from this review demonstrate that metal clusters (e.g., Ni and Ru) in many cases provide a greater catalytic efficiency on a metal loading basis for CO2 methanation compared to SACs. In contrast, SAAs have demonstrated a notable positive effect on catalyst activity and/or selectivity for CO2 methanation, with studies having identified the benefit of a single-atom alloy structure in providing these enhancements. Therefore, the use of either supported metal clusters (rather than single atoms) or SAAs shows the most potential in maximising metal atom efficiency in thermocatalytic CO2 methanation.

Nanoparticles based on platinum group metals (PGMs) are effective for catalyzing reductions of widely occurring water contaminants, including nitrate (NO3-) and per- and poly-fluoroalkyl substances (PFAS).  This Short Article presents a new way to use PGMs that enable efficient use of hydrogen gas (H2) as the reductant to detoxify nitrate (NO3-), per- and poly-fluoroalkyl substances (PFAS), and other oxidized water contaminants.  The platform is a H2-based membrane catalytic-film reactor (MCfR).  The MCfR’s foundation is a Pd catalyst film that is in situ deposited on the outer surface of gas-transfer membranes.  H2 is provided to the membrane’s lumen, permeates the membrane’s wall, and is delivered directly to the base of the nanometer-thick catalytic film.  H2-delivery pressure, Pd loading on the membrane surface, and the alloying of Pd with other PGMs control the kinetics and selectivity of the reduction reactions.  The MCfR concept takes PGMs another step closer practical clean-water applications, by transitioning from suspended nanoparticles to immobilized nanofilms.

This is Part II of the review discussing the role of molecular platinum complexes in homogeneous catalysis, with a focus on Pt-NHC pre-catalysts introduced in Part I (1). The following sections are devoted to the development of platinum-catalysed hydrosilylation of alkenes and alkynes, providing both historical context and an overview of the evolution in the mechanistic understanding of this reaction, as well as the most recent advancements and alternatives based on non-platinum catalysts.

Abstract: In order to systematically sort out the current research status, application areas, and development direction of ozone in environmental catalysis, a bibliometric analysis of the relevant literature published in the Web of Science database from 2005 to 2025 was carried out. VOSviewer and CiteSpace software were utilized to view data from 1379 journal articles. Data visualization and analysis identified 5330 authors, 249 journals, and 1276 institutions. The results show that the number of publications in the field of ozone-related environmental catalysis is on an increasing trend, especially after 2017. China, Spain, the United States, Iran, and India are the main driving forces, with China being the most active country. The Chemical Engineering Journal and the Journal of Hazardous Materials are the journals that publish the most relevant research. Harbin Institute of Technology, University of Engineering and Technology Lahore and Beijing Forestry University are the three institutions that publish the most literature. Currently, a more complete theoretical framework and research methodology on ozone environmental catalysis have been developed worldwide. However, the research network is too centralized, with fewer frontier peripheral branches. The research focus has gradually shifted from the early direct oxidation of ozone to the design of catalytic materials, radical modulation and multi-technology coupling (photocatalysis, plasma), and in recent years, more attention has been paid to the synergistic degradation of complex pollutants (antibiotics, VOCs) and the optimisation of the green and sustainable processes. It is necessary to overcome the bottlenecks of catalyst stability, energy consumption and by-product control, and promote the scale-up of ozone catalysis technology in water treatment and air purification. The present study is of great importance for a better understanding and further supporting the research of ozone environmental catalytic processes.