Maximizing the utilization of noble metals is crucial for applications such as catalysis. We found that the minimum loading of platinum for optimal performance in the hydroconversion of n -alkanes for industrially relevant bifunctional catalysts could be reduced by a factor of 10 or more through the rational arranging of functional sites at the nanoscale. Intentionally depositing traces of platinum nanoparticles on the alumina binder or the outer surface of zeolite crystals, instead of inside the zeolite crystals, enhanced isomer selectivity without compromising activity. Separation between platinum and zeolite acid sites preserved the metal and acid functions by limiting micropore blockage by metal clusters and enhancing access to metal sites. Reduced platinum nanoparticles were more active than platinum single atoms strongly bonded to the alumina binder.

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Supported nickel nanoparticles are promising catalysts for the methanation of CO2. The role of nickel particle size on activity and selectivity in this reaction is a matter of debate. We present a study of metal particle size effects on catalytic stability, activity and selectivity, using nickel on graphitic carbon catalysts. Increasing the Ni particle size from 4 to 8 nm led to a higher catalytic activity, both per gram of nickel and normalized surface area. However, the apparent activation energy remained the same (∼105 kJ mol−1). Comparing experiments at atmospheric to 30 bar pressure demonstrates the importance of testing under industrially relevant pressures; the highest selectivity is obtained at high CO2 conversions and pressures. Finally, the selectivity was particle size‐dependent. The largest particles were not only most active but also most selective to methane. With this work we contribute to the ongoing debate about Ni particle size effects in CO2 methanation.

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Colloidal heteronanocrystals allow for the synergistic combination of properties of different materials. For example, spatial separation of the photogenerated electron and hole can be achieved by coupling different semiconductors with suitable band offsets in one single nanocrystal, which is beneficial for improving the efficiency of photocatalysts and photovoltaic devices. From this perspective, axially segmented semiconductor heteronanorods with a type-II band alignment are particularly attractive since they ensure the accessibility of both photogenerated charge carriers. Here, a two-step synthesis route to Cu 2 –x S/CuInS 2 Janus-type heteronanorods is presented. The heteronanorods are formed by injection of a solution of preformed Cu 2 –x S seed nanocrystals in 1-dodecanethiol into a solution of indium oleate in oleic acid at 240 °C. By varying the reaction time, Janus-type heteronanocrystals with different sizes, shapes, and compositions are obtained. A mechanism for the formation of the heteronanocrystals is proposed. The first step of this mechanism consists of a thiolate-mediated topotactic, partial Cu + for In 3+ cation exchange that converts one of the facets of the seed nanocrystals into CuInS 2 . This is followed by homoepitaxial anisotropic growth of wurtzite CuInS 2 . The Cu 2 –x S seed nanocrystals also act as sacrificial Cu + sources, and therefore, single composition CuInS 2 nanorods are eventually obtained if the reaction is allowed to proceed to completion. The two-stage seeded growth method developed in this work contributes to the rational synthesis of Cu 2 –x S/CuInS 2 heteronanocrystals with targeted architectures by allowing one to exploit the size and faceting of premade Cu 2 –x S seed nanocrystals to direct the growth of the CuInS 2 segment.

Converting CO2 into value-added chemicals and fuels, such as methanol, is a promising approach to limit the environmental impact of human activities. Conventional methanol synthesis catalysts have shown limited efficiency...

In this work, we discuss the role of manganese oxide as a promoter in Cu catalysts supported on graphitic carbon during hydrogenation of CO2 and CO. MnOx is a selectivity modifier in an H2/CO2 feed and is a highly effective activity promoter in an H2/CO feed. Interestingly, the presence of MnOx suppresses the methanol formation from CO2 (TOF of 0.7 ⋅ 10−3 s−1 at 533 K and 40 bar) and enhances the low‐temperature reverse water‐gas shift reaction (TOF of 5.7 ⋅ 10−3 s−1) with a selectivity to CO of 87 %C. Using time‐resolved XAS at high temperatures and pressures, we find significant absorption of CO2 to the MnO, which is reversed if CO2 is removed from the feed. This work reveals fundamental differences in the promoting effect of MnOx and ZnOx and contributes to a better understanding of the role of reducible oxide promoters in Cu‐based hydrogenation catalysts.