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C2 hydrocarbons are important intermediates in petrochemical industry. Cryogenic rectification is broadly used to separate mixed C2 hydrocarbon gas to obtain pure C2 products. However, this process is very energyconsuming. Employing membrane separation technology to separate mixed gases can effectively reduce costs and energy consumption. Single-layer porous graphene membranes have great potential for mixed C2 hydrocarbons gas separation because of their outstanding separation performance; however, relevant studies are scarce. Herein, molecular dynamics simulations are applied to study the effect on the efficiency and selectivity of C2 hydrocarbons gas separation by single-layer porous graphene membranes with different pore sizes, pore shapes, and modified functional groups. The results show that the single-layer porous graphene membranes with pore sizes of 0.444-0.484 nm facilitate ethane retention with high ethylene passability. High gas passability and selectivity are determined for circular and oval pores, respectively. Oval pores with a short diameter of 0.510 nm and a long diameter of 1.164 nm are able to effectively pass ethylene molecules while retaining ethane molecules. A pore size of 0.596 nm with the pore being modified with two carboxyl groups can retain ethylene and pass acetylene. Our simulation results provide theoretical insights into the design of single-layer porous graphene membranes to separate C2 hydrocarbons gases efficiently and selectively. [ABSTRACT FROM AUTHOR]

Vanadium flow batteries (VFBs) face a challenge with the low reaction rates of the V(II)/V(III) redox couple, which limits the performance of VFBs. Additionally, the negative electrode in VFBs is often accompanied by the persistent hydrogen evolution reaction (HER), which is difficult to eliminate. Therefore, understanding the spatial distribution of activity on the negative electrode and the HER side reaction on the electrode surface is of critical importance. This study proposes a weak measurement imaging method to characterize the spatial distribution of surface activity and HER onset potential on the negative electrode in VFBs). This method enables the visualization and in situ detection of key parameters such as the absolute values of |ipa|, |ipc|, |∆E|, |ipc/ipa|, and the HER onset potential. By comparing three different types of graphite felts with varying activity levels, it validates the feasibility of this method. Furthermore, electrochemical stability tests are conducted to study the electrodes repeatability, uniformity, and durability. This method holds promise in guiding the design of electrodes with enhanced activity, good reversibility, minimized HER side reactions, and uniform distribution. [ABSTRACT FROM AUTHOR]

Developing highly efficient oxygen evolution reaction (OER) catalyst for the acidic corrosive operating conditions is a challenging task. Herein, we report the synthesis of uniform RuO2 clusters with ∼ 2 nm in size via electrochemical leaching of Sr from SrRuO3 ceramic in acid. The RuO2 clusters exhibit ultrahigh OER activity with overpotential of ∼ 160 mV at 10 mA·cmgeo−2 in 1.0 M HClO4 solution for 30-h testing. The extended X-ray absorption fine structure measurement reveals enlarged Jahn-Teller distortion of RuO octahedra in the RuO2 clusters compared to its bulk counterpart. Density function theory calculations show that the enhanced Jahn-Teller distortion can improve the intrinsic OER activity of RuO2. [ABSTRACT FROM AUTHOR]

Electrochemical nitrate reduction reaction (NO 3 RR) is a promising approach to realize ammonia generation and wastewater treatment. However, the transformation from NO 3 - to NH 3 involves multiple proton-coupled electron transfer processes and by-products (NO 2 - , H 2 , etc.), making high ammonia selectivity a challenge. Herein, a two-phase nanoflower P-Cu/Co(OH) 2 electrocatalyst consisting of P-Cu clusters and P-Co(OH) 2 nanosheets is designed to match the two-step tandem process (NO 3 - to NO 2 - and NO 2 - to NH 3 ) more compatible, avoiding excessive NO 2 - accumulation and optimizing the whole tandem reaction. Focusing on the initial 2e - process, the inhibited * NO 2 desorption on Cu sites in P-Cu gives rise to the more appropriate NO 2 - released in electrolyte. Subsequently, P-Co(OH) 2 exhibits a superior capacity for trapping and transforming the desorbed NO 2 - during the latter 6e - process due to the thermodynamic advantage and contributions of active hydrogen. In 1 m KOH + 0.1 m NO 3 - , P-Cu/Co(OH) 2 leads to superior NH 3 yield rate of 42.63 mg h - 1  cm - 2 and NH 3 Faradaic efficiency of 97.04% at -0.4 V versus the reversible hydrogen electrode. Such a well-matched two-step process achieves remarkable NH 3 synthesis performance from the perspective of optimizing the tandem catalytic reaction, offering a novel guideline for the design of NO 3 RR electrocatalysts., (© 2024 Wiley‐VCH GmbH.)

Aqueous flow batteries (AFBs) are promising long-duration energy storage system owing to intrinsic safety, inherent scalability, and ultralong cycle life. However, due to the thicker (3-5 mm) and heavier (300-600 g m -2 ) nature, the current used graphite felt (GF) electrodes still limit the volume/weight power density of AFBs. Herein, a lightweight (≈50 g m -2 ) and ultrathin (≈0.3 mm) carbon microtube electrode (CME) is proposed derived from a scalable one-step carbonization of commercial cotton cloth. The unique loose woven structure composed of carbon microtube endows CME with excellent conductivity, abundant active sites, and enhanced electrolyte transport performance, thereby significantly reducing polarization in working AFBs. As a consequence, CME demonstrates excellent cycling performance in pH-universal AFBs, including acidic vanadium flow battery (maximum power density of 632.2 mW cm -2 ), neutral Zn-I 2 flow battery (750 cycles with average Coulombic efficiency of 99.6%), and alkaline Zn-Fe flow battery (energy efficiency over 70% at 200 mA cm -2 ). More importantly, the estimated price of CME is only 5% of GF (≈3 vs ≈60 $ m -2 ). Therefore, it is reasonably anticipated that the lightweight and ultrathin CME may emerge as the next generation electrode for AFBs., (© 2024 Wiley‐VCH GmbH.)