H2-etching engineered oxygen vacancies on black TiO2−x to enhance the hot-electron flow and water-gas shift catalytic performance of Au catalysts.

Metal–CO2 batteries represent an economical and efficient CO2 utilization technique, which provides a mechanism combining CO2 reduction with electricity generation instead of electricity input. Existing metal–CO2 batteries generally work in a closed system by recycling CO2. In this study, a flow battery is designed with a hollow fiber of carbon nanotubes (cathode), Zn wire (anode), and 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (electrolyte). The battery can continuously consume CO2 to produce CH4 under ambient conditions and promptly output the gaseous product through the hollow fiber, with a Faradaic efficiency up to 94%. Simultaneously, the battery generates electricity, with an energy density of 288.3 Wh kg−1 (based on the zinc mass) and a stability up to 8 days. The high selectivity and efficiency of the battery is attributed to a water‐shuttling assisted proton mechanism and delicate electrode–electrolyte interplay. Moreover, the Zn anode is electrochemically renewed and the battery assembled with the regenerated Zn anode restores battery performances to the former level. The renewable characteristic implies that, if the regeneration of Zn anode is coupled to excessive renewable energy sources, then the Zn–CO2 flow battery will be promising to accomplish a net reduction of CO2 emission.

The surface structure of supports is crucial to fabricate efficient supported catalysts for water-gas shift (WGS). Here, hardly reducible ZrO was etched with hydrogen (H), aiming to modify surface structures with sufficient stable oxygen vacancies. After deposition of gold species, the obtained khaki ZrO-H notably improved WGS catalytic activities and stabilities in comparison to the traditional white ZrO. The characterization results and quantitative analysis indicate that sufficient surface oxygen vacancies of ZrO-H support give rise to more metallic Au species and higher microstrain, which all boost WGS catalytic activities. Furthermore, optoelectronic properties were successfully used to correlate with their WGS thermocatalytic activities, and then a modified electron flow process was proposed to understand the WGS pathway. For one thing, the introduction of surface oxygen vacancies narrowed the band gap of ZrO and decreased the Ohmic barrier, which facilitated the flow of "hot-electron". For another thing, the conduction band electrons can be easily trapped by oxygen vacancies of ZrO supports, and then these trapped electrons immediately take part in reduction of HO to H. Thus, the electron recombination was suppressed and the WGS catalytic activity was improved. It is worth extending H-etching technology to improve other thermocatalytic reactions.

Eugenol has been widely used in medicine due to its antibacterial, anti-inflammatory, antioxidant, anticancer and analgesic properties. The present study was designed to investigate the effects of eugenol on the cariogenic properties of Streptococcus mutans and dental caries development in rats. Eugenol demonstrated significant inhibitory effects against acid production by S. mutans. The synthesis of water-insoluble glucans by glucosyltransferases was reduced by eugenol. Eugenol also markedly suppressed the adherence of S. mutans to saliva-coated hydroxyapatite beads. Furthermore, topical application of eugenol reduced the incidence and severity of carious lesions in rats. These results suggest that the natural compound eugenol may be a useful therapeutic agent for dental caries.