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The coverage of *CO and *H intermediates on the surface of a catalyst plays a pivotal role in determining the selectivity towards C1 or C2 products in the electrochemical CO2 reduction reaction (CO2RR). In this study, we engineered two types of interfaces involving copper and rare earth metal oxides, specifically Cu/CeOx and Cu/CuCeOx solid solution, which exhibit enhanced binding affinities for *H and *CO adsorbates in the CO2RR, respectively. As a result, the Cu/CuCeOx catalyst delivered an ethylene faradaic efficiency of 40.2% at a partial current density of −245.7 mA cm−2, whereas the Cu/CeOx catalyst presented a methane faradaic efficiency of 38.6% at a partial current density of −198.3 mA cm−2. Results of theoretical and experimental analyses have demonstrated that the Cu–Ce–Ox solid solution markedly enhances *CO adsorption by stabilizing Cu+ species, thereby favoring its dimerization to ethylene rather than converting to methane through hydrogenation. This investigation elucidates a strategy for directing the selective electroproduction of C1 or C2 compounds from the CO2RR by effectively manipulating *H and *CO adsorption on Cu/CeOx catalysts. [ABSTRACT FROM AUTHOR]

Removing gaseous elemental mercury (Hg0) from Hg-containing tail gas is a hot topic and a great challenge. In this study, we developed a novel cost-effective and ultralight material, namely Cl-doped protonated polyaniline-coated multiwall carbon nanotubes (Cl-PANI+@MWCNTs), which could remove 98.5% of Hg0 at a high space velocity of 200 000 h−1, also possessing excellent reusability, good water resistance, and high thermal stability. Based on characterization analyses combined with density functional theory (DFT) calculations, its creation and mechanisms could be deeply explained, indicating that the low oxidation state of PANI was a prerequisite to achieve excellent Hg0 removal owing to its functional unit of –NH–, which promotes the production of –NH+˙–Cl* via the protonation and Cl-doping treatments. During the reaction, Hg0 is first adsorbed by the –NH+˙– antibonding orbital and then bonds with the covalent Cl* on –NH+˙– to form HgClx≡PANI. Cost analyses indicated that removing 1 lb of Hg0 by using Cl-PANI+@MWCNTs was about 63-fold cheaper than the published polypyrrole (PPy) counterpart, moreover the Hg0 dynamical adsorption capacity and the breakthrough time were increased by 3.2 times (7.43 mg g−1vs. 1.76 mg g−1, 52.6 h vs. 12.6 h) if taking the removal efficiency of 90% as the breakthrough point. The novel material proposed in this study is of great significance for the development of Hg0-removal technology. [ABSTRACT FROM AUTHOR]

In electrochemical water splitting, the balance between water dissociation step and the hydrogen adsorption on the catalysts is an ongoing challenge. Herein, Bi2O3, an inactive catalyst for the hydrogen evolution reaction (HER) caused by its unfavourable hydrogen adsorption Gibbs free energy (ΔGH*), is activated by an in situ phase engineering strategy for efficient HER electrocatalysis in alkaline media. Through this strategy, two-dimensional (2D) dual active Bi2O3 nanosheets with both BixNi alloy phases and α-Bi2O3 were fabricated to simultaneously catalyse the water dissociation step and the hydrogen formation step during an alkaline HER. In combination with the advantages of 2D nanomaterials and dual active catalytic sites, this phase engineered Bi2O3-based catalyst exhibited much improved alkaline HER performance. The modulated catalyst demonstrated an overpotential of 127 mV (at j = 10 mA cm−2) and a Tafel slope of 92 mV dec−1 in 1 M KOH, and is exceptional compared with other Bi2O3-based HER electrocatalysts. This work not only provides an innovative way to activate HER-inferior bismuth-based catalysts, but also offers new insights into the design of dual active catalysts for sluggish alkaline HER catalysis. [ABSTRACT FROM AUTHOR]

Nanoscale zero-valent iron has been considered to be the most promising electrocatalyst for denitrification due to its abundant resources, low price and non-toxicity. Nevertheless, the low utilization of active ingredients, inferior removal capacities (mg N g−1 Fe), and poor nitrogen selectivity are still major challenges during practical nitrate reduction. Herein, we have synthesized a one-dimensional architecture with homogeneously distributed Fe/Fe3C nanoparticles immobilized in a monodispersed carbonaceous matrix, embedded in ultra-high N-doped carbon nanofibers (Fe/Fe3C-NCNF) via a simple electrospinning strategy followed by confined reduction under a H2 atmosphere. The as-prepared Fe/Fe3C-NCNF nanostructure features well-dispersed Fe/Fe3C nanoparticles, confined reactive spaces, an interconnected nanofiber framework, and rich nitrogen doping sites, which are beneficial for integrating the synergistic catalytic effect of Fe and Fe3C, providing high-reactivity sites, boosting electron transfer, enlarging the catalyst–electrolyte interface and enhancing the surface adsorption capacity. The results reveal ultra-high nitrogen selectivity of 95% within 6 h and nearly 100% in 12 h, which are superior to other reported catalysts, and a maximum removal capacity of 2928.42 mg N g−1 Fe can be achieved, greatly improving the utilization of active ingredients. In addition, the catalysis material also shows good catalysis stability due to its structural features. The results of this study provide broad potential for the further development of iron-based functional nanostructures for electrocatalytic denitrification. [ABSTRACT FROM AUTHOR]

Heterogeneous catalysts which show high catalytic performance, structural stability, and low toxicity, are greatly required to efficiently degenerate organic pollutants in waste water in advanced oxidation processes (AOPs). In this paper, a mesoporous Cu–Mn/TiO2 composite heterogeneous catalyst was successfully prepared, which has a stable crystalline TiO2 mesostructure as the support, and well-dispersed Cu–Mn oxides as the catalytic active sties. Its Cu, Mn content is measured to be 5.7 and 6.0 wt%, and the BET surface area is measured to be 97 m2 g−1 with a pore size of ∼6.0 nm and pore volume of 0.15 cm3 g−1. Using the prepared Cu–Mn/TiO2 composite as an AOPs catalyst for the degeneration of Acid Red 1, it can efficiently (＞99%) degenerate the model pollutant in water within only 90 min. Compared with homogeneous catalysts, it can retain its catalytic performance over a wide pH range (3–9) and can be recycled for at least five times while still possessing the decolorization efficiency of 89%. By analyzing the catalytic process, a possible catalytic procedure for the degradation of Acid Red 1 has been proposed. Furthermore, using bulk Cu–Mn oxides, Cu–Mn/P25, and Cu–Mn/SBA-15 as reference catalysts, we propose that the excellent catalytic performance of Cu–Mn/TiO2 could be ascribed to the anatase mesoporous TiO2, which not only offers a stable matrix with high surface area for Cu–Mn catalysts, but also serves as a type of catalytic promoter for the synergistic catalytic degeneration of Acid Red 1. [ABSTRACT FROM AUTHOR]

Highly branched TiO2 interpenetrating network architectures decorated with SnO2 nanocrystals were fabricated through a sacrificial-template approach for selective catalytic reduction of NO with ammonia. Such unique architectures demonstrate outstanding catalytic activity for NO conversion (∼90%), high N2 selectivity (∼100%), good stability and strong resistance to SO2 and H2O poisoning over a broad temperature range (75–325 °C). [ABSTRACT FROM AUTHOR]