Pulsed Electrolysis Promotes CO2 Reduction to Ethanol on Heterostructured Cu2O/Ag Catalysts.

The electrochemical conversion of carbon dioxide (CO2) into ethanol with high added value has attracted increasing attention. Here, an efficient catalyst with abundant Cu2O/Ag interfaces for ethanol production under pulsed CO2 electrolysis is reported, which is composed of Cu2O hollow nanospheres loaded with Ag nanoparticles (named as se-Cu2O/Ag). The CO2-to-ethanol Faradaic efficiency is prominently improved to 46.3% at a partial current density up to 417 mA cm-2 under pulsed electrolysis conditions in a neutral flow cell, notably outperforming conventional Cu catalysts during static electrolysis. In situ spectroscopy reveals the stabilized Cu+ species of se-Cu2O/Ag during pulsed electrolysis and the enhanced adsorbed CO intermediate (*CO)coverage on the heterostructured catalyst. Density functional theory (DFT) calculations further confirm that the Cu2O/Ag heterostructure stabilizes the *CO intermediate and promotes the coupling of *CO and adsorbed CH intermediate (*CH). Meanwhile, the stable Cu+ species under pulsed electrolysis favor the hydrogenation of adsorbed HCCOH intermediate (*HCCOH) to adsorbed HCCHOH intermediate (*HCCHOH) on the pathway to ethanol. The synergistic effect between the enhanced generation of *CO on Cu2O/Ag and regenerated Cu+ species under pulsed electrolysis steers the reaction pathway toward ethanol. This work provides some insights into selective ethanol production from CO2 electroreduction via combined catalyst design and non-steady state electrolysis.

Self-Limited Formation of Cobalt Nanoparticles for Spontaneous Hydrogen Production through Hydrazine Electrooxidation.

Hydrogen (H2 ) has emerged as a highly promising energy carrier owing to its remarkable energy density and carbon emission-free properties. However, the widespread application of H2 fuel has been limited by the difficulty of storage. In this work, spontaneous electrochemical hydrogen production is demonstrated using hydrazine (N2 H4 ) as a liquid hydrogen storage medium and enabled by a highly active Co catalyst for hydrazine electrooxidation reaction (HzOR). The HzOR electrocatalyst is developed by a self-limited growth of Co nanoparticles from a Co-based zeolitic imidazolate framework (ZIF), exhibiting abundant defective surface atoms as active sites for HzOR. Notably, these self-limited Co nanoparticles exhibit remarkable HzOR activity with a negative working potential of -0.1 V (at 10 mA cm-2 ) in 0.1 m N2 H4 /1 m KOH electrolyte. Density functional theory (DFT) calculations are employed to validate the superior performance of low-coordinated Co active sites in facilitating HzOR. By taking advantage of the potential difference between HzOR and the hydrogen evolution reaction (HER), a novel HzOR||HER electrochemical system is developed to spontaneously produce H2 without external energy input. Overall, the work offers valuable guidance for developing active HzOR catalyst. The novel HzOR||HER electrochemical system represents a promising and innovative solution for energy-efficient hydrogen production.

A new insight into the CaO-induced inhibition pathways on PCDD/F formation: Metal passivation, dechlorination and hydroxide substitution.

Ca-based inhibitors (especially CaO) for PCDD/F (polychlorinated dibenzo-p-dioxin and dibenzofuran) formation are considered as economic inhibitors with low toxicity and strong adsorption of acidic gases (e.g., HCl, Cl2, and SOx), whereas the insight understanding of its inhibition mechanisms is scarcely explored. Herein, CaO was used to inhibit the de novo reaction for PCDD/F formation (250-450 °C). The evolution of key elements (C, Cl, Cu, and Ca) combined with theoretical calculations was systematically investigated. The concentrations and distribution of PCDD/Fs demonstrated the significant inhibition effect of CaO on I-TEQ (international toxic equivalency) concentrations of PCDD/Fs (inhibition efficiencies: > 90 %) and hepta~octa chlorinated congeners (inhibition efficiencies: 51.5-99.8 %). And the conditions (5-10 % CaO, 350 °C) were supposed to be the preferred conditions applied in real MSWIs (municipal solid waste incinerators). CaO significantly suppressed the chlorination of carbon matrix (superficial organic Cl (CCl) reduced from 16.5 % to 6.5-11.3 %) and the formation of unsaturated hydrocarbons or aromatic carbon (superficial CC decreased from 6.7 % to 1.3-2.1 %). Also, CaO promoted the dechlorination of Cu-based catalysts and Cl solidification (e.g., conversion of CuCl2 to CuO, and formation of CaCl2). The dechlorination phenomenon was validated by the dechlorination of highly chlorinated PCDD/F-congeners (via DD/DF chlorination pathways). Density functional theory calculations revealed that CaO facilitated the substitution of Cl by -OH on the benzene ring to inhibit the polycondensation of the chlorobenzene and chlorophenol (Gibbs free energy reduced from +74.83 to -36.62 and - 148.88 kJ/mol), which also indicates the dechlorination effect of CaO on de novo synthesis.

Enhanced NH3 Synthesis from Air in a Plasma Tandem-Electrocatalysis System Using Plasma-Engraved N-Doped Defective MoS2.

We have developed a sustainable method to produce NH3 directly from air using a plasma tandem-electrocatalysis system that operates via the N2-NOx-NH3 pathway. To efficiently reduce NO2- to NH3, we propose a novel electrocatalyst consisting of defective N-doped molybdenum sulfide nanosheets on vertical graphene arrays (N-MoS2/VGs). We used a plasma engraving process to form the metallic 1T phase, N doping, and S vacancies in the electrocatalyst simultaneously. Our system exhibited a remarkable NH3 production rate of 7.3 mg h-1 cm-2 at -0.53 V vs RHE, which is almost 100 times higher than the state-of-the-art electrochemical nitrogen reduction reaction and more than double that of other hybrid systems. Moreover, a low energy consumption of only 2.4 MJ molNH3-1 was achieved in this study. Density functional theory calculations revealed that S vacancies and doped N atoms play a dominant role in the selective reduction of NO2- to NH3. This study opens up new avenues for efficient NH3 production using cascade systems.

Expression of Skp2 and p27kip1 proteins in hypopharyngeal squamous cell carcinoma and its clinical significance.

The aim of the present study was to determine the effect of S-phase kinase-associated protein 2 (Skp2) and cyclin-dependent kinase inhibitor p27kinase-interacting protein 1 (p27kip1) protein expression on the occurrence and development of hypopharyngeal squamous cell carcinoma. The protein expression levels of Skp2 and p27kip1 were detected in 42 hypopharyngeal squamous cell carcinoma and 15 normal hypopharyngeal mucous membrane specimens using the an immunohistochemical PV-9000 two-step method. The expression levels of Skp2 protein were significantly different in hypopharyngeal squamous cell carcinomas and normal hypopharyngeal mucous membranes (61.90 vs. 26.67%; P<0.05). By contrast, the protein expression levels of Skp2 were significantly positively correlated with tumor T stage (rs=0.329, P<0.05) and cervical lymph node metastasis (rs=0.402, P<0.05). Furthermore, the expression levels of p27kip1 protein were significantly different in hypopharyngeal squamous cell carcinomas and normal hypopharyngeal mucous membranes (11.9 vs. 53.33%; P<0.05), while p27kip1 protein expression was significantly negatively correlated with tumor T-stage (rs=-0.351, P<0.05) and cervical lymph node metastasis (rs=-0.371, P<0.05). Notably, a significant negative correlation was observed between the expression levels of Skp2 and p27kip1 proteins in hypopharyngeal squamous cell carcinoma (P<0.05). In addition, abnormal expression levels of Skp2 and p27kip1 proteins were observed in hypopharyngeal squamous cell carcinoma tissues. Thus, Skp2 and p27kip1 proteins may be involved in the development of hypopharyngeal squamous cell carcinoma. The current study proposed that combined detection of Skp2 and p27kip1 may be useful for assessing the characteristics and prognosis of hypopharyngeal squamous cell carcinoma.