Lindlar catalysts comprising of palladium/calcium carbonate modified with lead acetate and quinoline are widely employed industrially for the partial hydrogenation of alkynes. However, their use is restricted, particularly for food, cosmetic and drug manufacture, due to the extremely toxic nature of lead, and the risk of its leaching from catalyst surface. In addition, the catalysts also exhibit poor selectivities in a number of cases. Here we report that a non-surface modification of palladium gives rise to the formation of an ultra-selective nanocatalyst. Boron atoms are found to take residence in palladium interstitial lattice sites with good chemical and thermal stability. This is favoured due to a strong host-guest electronic interaction when supported palladium nanoparticles are treated with a borane tetrahydrofuran solution. The adsorptive properties of palladium are modified by the subsurface boron atoms and display ultra-selectivity in a number of challenging alkyne hydrogenation reactions, which outclass the performance of Lindlar catalysts.

Today's chemical industry is a pillar of our modern society, but it heavily relies on the consumption of non-renewable fossil fuels. The reaction conditions required to drive most of the chemical processes require high energy input, resulting in the consumption of significant amounts of dwindling reserves of fossil fuels. Therefore, more sustainable pathways are much sought after to reduce the dependence on fossil fuels and ameliorate the effects of climate change. Inspired by photosynthesis and its ability to convert CO 2 and H 2 O to hydrocarbons, this Perspective focuses on recent advances in catalytic small-molecule activation and conversion. It will consider reactions of C-H (CH 4 , benzene), C=O (CO and CO 2), NhN bonds, and other fine chemicals syntheses (e.g., CC and S-S bond coupling), driven by either solar or thermal energy. The paper also discusses the future opportunities and challenges by highlighting some strategies for the development of efficient solar or thermal catalysis processes.

Altering the exposed facet of CeO2 nanocrystallites and hence the control of surface chemistry on the nano level have been shown to significantly change their performances in various catalytic reactions. The chemical state of surface Ce, which is associated with Lewis acidity and hence the adsorption/activation energy of reactants on the surface, is expected to vary with their hosted facets. Unfortunately, traditional surface tools fail to differentiate/quantify them among hosted facets and thus have led to different interpretations among researchers in the past decades. Herein, probe-assisted nuclear magnetic resonance is employed for the surface investigation of different CeO2 facets. They not only allow differentiation of the surface Ce atoms between hosted facets at high resolution but can also provide their corresponding concentrations. The as-established facet fingerprint of CeO2 can thus report on the facet distribution/concentration of a given CeO2 sample. Dephosphorylation and H2O2 reduction were tested as probe reactions to demonstrate the importance of obtaining comprehensive surface Ce information for the active site identification and the rational design of CeO2-based catalysts. Around 1000 and 4500% increase in activity of those reactions can be easily achieved on pristine CeO2 without further surface engineering when its terminal facet is wisely chosen. Our results thus imply that the basic surface knowledge of even a simple catalyst can be more important than the continuous development of their fancy derivatives without clear guidance.

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Low power consumption, fast response and quick recovery times are important parameters for gas sensors performance. Herein, we report the experimental and theoretical studies of ZnO and Cr doped ZnO nanostructures used in low temperature (50 °C) sensors for the detection of CO. The synthesized films were characterized by XRD, UV-Vis, FE-SEM and EDX. The XRD patterns for the ZnO and 0.5 wt% Cr/ZnO films confirm the formation of a single-phase hexagonal wurtzite structure. The reduction of the ZnO optical band gap from 3.12 eV to 2.80 eV upon 0.5 wt% Cr doping is well correlated with the simulation data. The FE-SEM images of the films show spherical morphology with the estimated particle sizes of about ~40 nm and ~ 25 nm were recorded for the ZnO and 0.5 wt% Cr/ZnO films, respectively. Enhanced gas sensing performance is achieved with Cr doping and the sensitivity of ZnO increases from 9.65% to 65.45%, and simultaneously decreasing the response and recovery times from 334.5 s to 172.3 s and from 219 s to 37.2 s, respectively. These improvements in gas sensing performance are due to the reduction in particle size and optical band gap, and an increase in specific surface area.