Electrochemical carbon monoxide reduction is a promising strategy for the production of value-added multicarbon compounds, albeit yielding diverse products with low selectivities and Faradaic efficiencies. Here, copper single atoms anchored to Ti3C2Tx MXene nanosheets are firstly demonstrated as effective and robust catalysts for electrochemical carbon monoxide reduction, achieving an ultrahigh selectivity of 98% for the formation of multicarbon products. Particularly, it exhibits a high Faradaic efficiency of 71% towards ethylene at −0.7 V versus the reversible hydrogen electrode, superior to the previously reported copper-based catalysts. Besides, it shows a stable activity during the 68-h electrolysis. Theoretical simulations reveal that atomically dispersed Cu–O3 sites favor the C–C coupling of carbon monoxide molecules to generate the key *CO-CHO species, and then induce the decreased free energy barrier of the potential-determining step, thus accounting for the high activity and selectivity of copper single atoms for carbon monoxide reduction.

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Energy crisis and environmental pollution trigger the development of efficient and robust electrochemical energy conversion and storage technologies. [1-3] The electrocatalytic reactions, such as hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR), undoubtedly play key roles in developing renewable energy conversion devices, Development of cost-effective, active trifunctional catalysts for acidic oxygen reduction (ORR) as well as hydrogen and oxygen evolution reactions (HER and OER, respectively) is highly desirable, albeit challenging. Herein, singleatomic Ru sites anchored onto Ti 3 C 2 T x MXene nanosheets are first reported to serve as trifunctional electrocatalysts for simultaneously catalyzing acidic HER, OER, and ORR. A half-wave potential of 0.80 V for ORR and small overpotentials of 290 and 70 mV for OER and HER, respectively, at 10 mA cm −2 are achieved. Hence, a low cell voltage of 1.56 V is required for the acidic overall water splitting. The maximum power density of an H 2-O 2 fuel cell using the as-prepared catalyst can reach as high as 941 mW cm −2. Theoretical calculations reveal that isolated Ru-O 2 sites can effectively optimize the adsorption of reactants/intermediates and lower the energy barriers for the potentialdetermining steps, thereby accelerating the HER, ORR, and OER kinetics.

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Laser spectroscopy outperforms electrochemical and semiconductor gas sensors in selectivity and environmental survivability. However, the performance of the state-of-the-art laser sensors is still insufficient for many high precision applications. Here, we report mode-phasedifference photothermal spectroscopy with a dual-mode anti-resonant hollow-core optical fiber and demonstrate all-fiber gas (acetylene) detection down to ppt (parts-per-trillion) and <1% instability over a period of 3 hours. An anti-resonant hollow-core fiber could be designed to transmit light signals over a broad wavelength range from visible to infrared, covering molecular absorption lines of many important gases. This would enable multi-component gas detection with a single sensing element and pave the way for ultra-precision gas sensing for medical, environmental and industrial applications.

Here, we demonstrate that at ambient conditions, nickel-iron layered double hydroxide nanosheets array can achieve a promising NORR performance, delivering a maximal faradaic efficiency of 82% and a corresponding yield...

Ambient NH 3 electrosynthesis from NO reduction reaction (NORR) is attractive in replacing the industrial Haber-Bosch route; however, the competitive hydrogen evolution reaction (HER) in aqueous electrolyte typically induces a limited selectivity and activity toward NH 3 production. Herein, hierarchical P-doped MoS 2 nanospheres are developed as the NORR electrocatalyst in an ionic liquid (IL) electrolyte for catalyzing the reduction of NO to NH 3 with a maximal Faradaic efficiency of 69 % (À 0.6 V vs RHE) and a peak yield rate of 388.3 μg h À 1 mg cat.À 1 (À 0.7 V vs RHE), both of which are comparable to the best-reported results. Moreover, the catalyst also shows stable NORR activity over 30 h and 6 cycles. Theoretical analyses further reveal that the P dopants in MoS 2 facilitate the activation and hydrogenation of NO. Besides, the employment of hydrophobic IL electrolyte also slows down the HER kinetics effectively.