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Achieving control over the transport properties of charge-carriers is a crucial aspect of realizing high-performance electronic materials. In metal-halide perovskites, which offer convenient manufacturing traits and tunability for certain optoelectronic applications, this is challenging: The perovskite structure itself, poses fundamental limits to maximum dopant incorporation. Here, we demonstrate an organic modifier incorporation strategy capable of modulating the electronic density of states in halide tin perovskites without altering the perovskite lattice, in a similar fashion to substitutional doping in traditional semiconductors. By incorporating organic small molecules and conjugated polymers into cesium tin iodide (CsSnI3) perovskites, we achieve carrier density tunability over 2.7 decades, transition from a semiconducting to a metallic nature, and high electrical conductivity exceeding 200 S/cm. We leverage these tunable and enhanced electronic properties to achieve a thin-film, lead free, thermoelectric material with a near room-temperature figure-of-merit (ZT) of 0.21, the highest amongst all halide perovskite thermoelectrics. Our strategy provides an additional degree of freedom in the design of halide perovskites for optoelectronic and energy applications.

Among all catalytic natural gas valorization processes, methane dehydroaromatization (MDA) still has a great potential to be utilized at an industrial level. Although the use of Mo/H-ZSM-5 as an MDA catalyst was first reported almost three decades ago, the process is yet to be industrialized, because of its inherent challenges. In order to improve the overall catalytic performance and lifetime, the co-feeding of water constitutes a promising option, because of its abundance and nontoxicity. Although water’s (limited) positive influence on catalyst lifetime has earlier been exhibited, the exact course of action (like mechanism or the water effect on active sites) is yet to be established. To bridge this knowledge gap, in this work, we have performed an in-depth investigation to elucidate the effects of water co-feeding over a well-dispersed Mo/H-ZSM-5 catalyst by using an array of advanced characterization techniques (nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry-temperature-programmed oxidation/mass spectroscopy (TG-TPO/MS), scanning transmission electron microscopy (STEM), N2physisorption, Raman spectroscopy, inductively coupled plasma-optical emission spectroscopy (ICP-OES)). Our results demonstrate that the addition of water results in the occurrence of steam reforming (of both coke and methane) in parallel to MDA. Moreover, the presence of water affects the reducibility of Mo sites, as corroborated with computational analysis to examine the state and locality of Mo sites under various water levels and transformation of the catalyst structure during deactivation. We anticipate that our comprehensive study of the structure-function relationship on Mo/H-ZSM-5 under humid MDA conditions will be beneficial for the development of future methane valorization technologies.

This contribution explains the origin of dramatic rate accelerations in chemical reactions taking place in/on aqueous electrosprays. We combine experiments with electrosprays and proton-nuclear magnetic resonance with quantum mechanics to systematically decouple genuine interfacial effects from non-equilibrium conditions., The recent application of electrosprays to characterize the air–water interface, along with the reports on dramatically accelerated chemical reactions in aqueous electrosprays, have sparked a broad interest. Herein, we report on complementary laboratory and in silico experiments tracking the oligomerization of isoprene, an important biogenic gas, in electrosprays and isoprene–water emulsions to differentiate the contributions of interfacial effects from those of high voltages leading to charge-separation and concentration of reactants in the electrosprays. To this end, we employed electrospray ionization mass spectrometry, proton nuclear magnetic resonance, ab initio calculations and molecular dynamics simulations. We found that the oligomerization of isoprene in aqueous electrosprays involved minimally hydrated and highly reactive hydronium ions. Those conditions, however, are non-existent at pristine air–water interfaces and oil–water emulsions under normal temperature and pressure. Thus, electrosprays should be complemented with surface-specific platforms and theoretical methods to reliably investigate chemistries at the pristine air–water interface.

The recent application of electrosprays to characterize the air-water interface, along with the reports on dramatically accelerated chemical reactions in aqueous electrosprays, have sparked a broad interest. Herein, we report on complementary laboratory and in silico experiments tracking the oligomerization of isoprene, an important biogenic gas, in electrosprays and isoprene-water emulsions to differentiate the contributions of interfacial effects from those of high voltages leading to charge-separation and concentration of reactants in the electrosprays. To this end, we employed electrospray ionization mass spectrometry, proton nuclear magnetic resonance, and quantum mechanical simulations. We found that the oligomerization of isoprene in aqueous electrosprays involved minimally hydrated and highly reactive hydronium ions. Those conditions, however, are non-existent at pristine air-water interfaces and oil-water emulsions under normal temperature and pressure. Thus, electrosprays should be complemented with surface-specific platforms and theoretical methods to reliably investigate chemistries at the pristine air-water interface., 16 pages and 6 figures in the main paper; 30 pages and 14 figures in total including supporting information