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Bipolar membranes (BPMs) have emerged as a promising solution for mitigating CO2 losses, salt precipitation and high maintenance costs associated with the commonly used anion‐exchange membrane electrode assembly for CO2 reduction reaction (CO2RR). However, the industrial implementation of BPM‐based zero‐gap electrolyzer is hampered by the poor CO2RR performance, largely attributed to the local acidic environment. Here, we report a backbone engineering strategy to improve the CO2RR performance of molecular catalysts in BPM‐based zero‐gap electrolyzers by covalently grafting cobalt tetraaminophthalocyanine onto a positively charged polyfluorene backbone (PF‐CoTAPc). PF‐CoTAPc shows a high acid tolerance in BPM electrode assembly (BPMEA), achieving a high FE of 82.6 % for CO at 100 mA/cm2 and a high CO2 utilization efficiency of 87.8 %. Notably, the CO2RR selectivity, carbon utilization efficiency and long‐term stability of PF‐CoTAPc in BPMEA outperform reported BPM systems. We attribute the enhancement to the stable cationic shield in the double layer and suppression of proton migration, ultimately inhibiting the undesired hydrogen evolution and improving the CO2RR selectivity. Techno‐economic analysis shows the least energy consumption (957 kJ/mol) for the PF‐CoTAPc catalyst in BPMEA. Our findings provide a viable strategy for designing efficient CO2RR catalysts in acidic environments. [ABSTRACT FROM AUTHOR]

Seawater electrolysis is an attractive way of making H2 in coastal areas, and NiFe‐based materials are among the top options for alkaline seawater oxidation (ASO). However, ample Cl− in seawater can severely corrode catalytic sites and lead to limited lifespans. Herein, we report that in situ carbon oxyanion self‐transformation (COST) from oxalate to carbonate on a monolithic NiFe oxalate micropillar electrode allows safeguard of high‐valence metal reaction sites in ASO. In situ/ex situ studies show that spontaneous, timely, and appropriate COST safeguards active sites against Cl− attack during ASO even at an ampere‐level current density (j). Our NiFe catalyst shows efficient and stable ASO performance, which requires an overpotential as low as 349 mV to attain a j of 1 A cm−2. Moreover, the NiFe catalyst with protective surface CO32− exhibits a slight activity degradation after 600 h of electrolysis under 1 A cm−2 in alkaline seawater. This work reports effective catalyst surface design concepts at the level of oxyanion self‐transformation, acting as a momentous step toward defending active sites in seawater‐to‐H2 conversion systems. [ABSTRACT FROM AUTHOR]

We report the large‐scale synthesis of photoluminescent single‐chain nanoparticles (SCNPs) by electrostatic‐mediated intramolecular crosslinking in a concentrated solution of 40 mg mL−1 by continuous addition of the free radical initiator. Poly(vinyl benzyl chloride) was charged by quaternization with vinyl‐imidazolium for the intramolecular crosslinking by using 2,2‐dimethoxy‐2‐phenylacetophenone (DMAP) as the radical initiator. Under the electrostatic repulsion thus interchain isolation, the intrachain crosslinking experiences the transition from coil through pearl‐necklace to globular state. The SCNPs demonstrate strong photoluminescence in the visible range when the non‐emissive units are confined thereby. Composition and microstructure of the SCNPs are tunable. The photoluminescent tadpole‐like Janus SCNP can be used to selectively illuminate interfacial membranes while stabilizing the emulsions. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous Zn batteries are potential for large‐scale electrochemical energy storage due to their low cost and high security. However, Zn metal anode suffers from the dendritic growth and interfacial hydrogen evolution reaction (HER), resulting in the deterioration of electrode/battery performance. Here we propose that both dendrites and HER are related to the water participated Zn2+ solvation structure‐Zn(H2O)62+ and thus can be resolved by transforming Zn(H2O)62+ to an anion‐type water‐free solvation structure‐ZnCl42−, which is achieved in traditional ZnSO4 aqueous electrolyte after adding chloride salt with a bulky cation (1‐ethyl‐3‐methylimidazolium chloride). The elimination of cation‐water interaction suppresses HER, while the electrostatic repulsion between Zn tips and the anion solvation structure inhibits dendrite formation. As a result, the electrolyte shows uniform Zn deposition with an average Zn plating/stripping Coulombic efficiency of ≈99.9 %, enabling a capacity retention of 78.8 % after 300 cycles in anode‐free Zn batteries with pre‐zincificated polyaniline as the cathode. This work provides a novel electrolyte design strategy to prevent HER and realize long‐lifespan metal anode. [ABSTRACT FROM AUTHOR]

Peristaltic crawling, which is the moving mechanism of earthworm‐like limbless creatures in narrow spaces, is a challenging target to mimic by using soft materials. Here we report an unprecedented hydrogel actuator that enables not only a peristaltic crawling motion but also reversing its direction. Our cylindrically processed hydrogel contains gold nanoparticles for photothermal conversion, a thermoresponsive polymer network for switching the electrical permittivity of the gel interior, and cofacially oriented 2D electrolytes (titanate nanosheets; TiNSs) to synchronously change their anisotropic electrostatic repulsion. When a hydrogel, which was designed to include cofacially oriented TiNSs along the cylindrical gel axis, is pointwisely photoirradiated with a visible‐light laser, it spatiotemporally expands immediately (<0.5 s) and largely (80 % of its original length) in an isovolumetric manner. When the irradiation spot is moved along the cylindrical gel axis, the hydrogel undergoes peristaltic crawling due to quick and sequential elongation/contraction events and moves oppositely toward the laser scanning direction. Thus, when the scanning direction is switched, the crawling direction is reversed. When gold nanorods are used in place of gold nanoparticles, the hydrogel becomes responsive to a near‐infrared light, which can deeply penetrate into bio tissues. Soft robot: An unprecedented photoresponsive hydrogel actuator enables earthworm‐like peristaltic crawling and reverses its direction by scanning with a laser spotlight. This anomalous optical control was made possible by a rapid, large, repeatable, spatiotemporal, and anisotropic photothermal deformation of a hydrogel that contains gold nanoparticles in titanate nanosheets. [ABSTRACT FROM AUTHOR]

Abstract: In our previous work, we have shown that “electrostatic forces”, when generated anisotropically in aqueous media by 2D electrolytes upon cofacial orientation, enable the formation of a hydrogel with an anisotropic parameter, as defined by the ratio of elastic moduli E⊥/E∥, of 3.0. Herein, we successfully developed the design strategy for a hydrogel with an anisotropic parameter of no less than 85. This value is not only 28 times greater than that of our previous anisotropic hydrogel but also 6 times larger than the current champion record in synthetic hydrogels (E⊥/E∥∼15). Firstly, we simply lowered ionic contaminants in the hydrogel and were able to enhance the anisotropic parameter from 3.0 to 18. Then, we chose a supporting polymer network allowing the hydrogel to carry a higher interior permittivity. Consequently, the anisotropic parameter was further enhanced from 18 to 85. Owing to the enhanced mechanical anisotropy, our new hydrogel displayed a superb ability of seismic isolation. [ABSTRACT FROM AUTHOR]

Electrochemical surface stress is important in nanomaterials because of their large surface-to-volume ratios, which lead to unique mechanical and electrocatalytic properties, but directly measuring this quantity has been challenging. Here we report on experimental determination of the surface stress, and associated electrochemical processes of a single gold nanowire with an optical imaging technique. We show that surface stress changes linearly and reversibly with the potential between 0 and 0.8 V versus Ag/AgCl, but abruptly with large hysteresis, associated with the oxidation and reduction of the nanowire, between 0.8 and 1.5 V. The potential derivative of the surface stress closely resembles the cyclic voltammograms. We described the observations in terms of anion adsorption and surface oxidation/reduction. This work demonstrates a new approach to study electrochemical processes and the associated surface stress changes of nanomaterials. [ABSTRACT FROM AUTHOR]