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Atmospheric water harvesting (AWH) is regarded as one of the promising strategies for freshwater production desirable to provide sustainable water for landlocked and arid regions. Hygroscopic materials have attracted widespread attention because of their water harvesting performance. However, the introduction of many inorganic salts often leads to aggregation and leakage issues in practical use. Here, polyzwitterionic hydrogels are developed as an effective AWH material platform. Via anti‐polyelectrolyte effects, the hygroscopic salt coordinated with polymer chains could capture moisture and enhance the swelling property, leading to a strong moisture sorption capacity. The hydrogel shows superior AWH performance (0.62 g g−1, 120 minutes for equilibrium at 30 % relative humidity) and produces 5.87 L kg−1 freshwater per day. It is anticipated that the polyzwitterionic hydrogels with unique salt‐responsive properties could provide new insights into the design and synthesis of next‐generation AWH materials. [ABSTRACT FROM AUTHOR]

As an eco‐friendly means, solar water purification has attracted substantial research interest regarding material design, system engineering, and energy management. However, the low water yield and relatively high cost essentially restrict its practical potential. Here, a hydrogel‐based ultrathin membrane (HUM) is developed to synergistically coordinate facilitated vapor transfer and environmental energy harvesting for solar‐driven membrane distillation. The evaporation front is directly exposed to an airflow, which fundamentally eliminates the temperature polarization induced energy consumption. As such, the humidity of the output flow is significantly increased, and thus the vapor collection ratio rises to over 80% to achieve a high water yield of 2.4 kg m–2 h–1 under one sun without any energy recycling and cooling accessories. The HUM with a raw material cost of $0.36 m–2 offers a competitive potential cost of freshwater production of about $0.3–1.0 m–3. This work demonstrates a promising membrane distillation strategy based on sustainable energy toward both decentralized water purification and large‐scale water treatment. [ABSTRACT FROM AUTHOR]

The broad application of metal-air batteries and fuel cells have been greatly limited due to their slow kinetics of oxygen electrodes involving the oxygen reduction reaction (ORR), and therefore the development of high-efficient, low-cost and high-reserve ORR electrocatalysts is of great significance. Herein, a hypersaline-protected pyrolysis strategy is presented for preparing 3D honeycombed cobalt, nitrogen co-doped carbon nanosheets (Co/N-CNS) by using eco-friendly biomass as a carbon and nitrogen source. During the hypersaline-protected pyrolysis, the pyridinic nitrogen-rich biomass facilitates the formation of highly active Co/N active sites among the resultant Co/N-CNS, while the templating-washing-drying cyclic utilization of salts creates honeycombed pore structures among the Co/N-CNS. Due to the structural features of honeycombed pores and uniform distributed active sites, the Co/N-CNS catalyst offers excellent ORR activity, high durability and methanol-tolerant performance in an alkaline electrolyte. As a demonstration, a primary Zn-air battery using the Co/N-CNS cathode delivers a high power density and excellent operating stability beyond that of commercial Pt/C cathode. [ABSTRACT FROM AUTHOR]

Abstract: A simple, low cost and nontoxic preparation method to obtain high performance oxygen reduction reaction (ORR) catalysts is of great significance in fuel cell fields. Herein, graphene nanoribbons (GNRs) with numerous graphitic edges are chosen as supporting material to hybridize with nitrogen atoms and cobalt oxide (Co3O4) through a simple one‐step hydrothermal reaction. With a high edge‐to‐plane ratio, the GNR sheets could increase the accessibility of N‐atom doping into the graphene edges to form active ORR sites, and be also interconnected with each other to form a conductive network, thus facilitating the fast electron transfer. The intimate contacts between Co3O4 nanoparticles and nitrogen‐doped GNRs (N‐GNRs) along with the porous structure impart the N‐GNR/Co3O4 hybrid with excellent ORR performance, which leads to a comparable onset‐potential to commercial Pt/C catalyst but larger current density, better long‐term stability and superior tolerance to crossover effects. [ABSTRACT FROM AUTHOR]

It is very important to develop a simple, efficient, and scaleable method for detection of dopamine (DA) with high sensitivity and selectivity to diagnose some serious neurological diseases. Herein, electro-catalysts for detection of DA are simply prepared based on Fe2O3 nanoparticles (NPs) decorated on highly porous carbon aerogels (CAs), which are derived from KOH activated graphene-polyimide aerogels. In the hierarchical nanocomposites (NCs), CAs provide large specific surface area, abundant mesopores, and macropores, and many sites for in situ growth of Fe2O3 NPs, thus effectively preventing the aggregation of Fe2O3 NPs. Moreover, CAs with 3D interconnected porous structures are able to shorten the charge transfer pathways through the intimate interaction between CAs and Fe2O3 NPs. Therefore, when applied as electro-catalysts for detection of DA, the optimized NC exhibits rapid amperometric response and a low detection limit of 0.109 × 10−6 m (S/N = 3), with a wide linear concentration range from 5 to 500 × 10−6 m. In addition, the oxidation peak of DA can be readily distinguished from the interference of uric acid and ascorbic acid. Therefore, the highly porous CAs derived from KOH activated graphene-polyimide aerogels are excellent substrates for in situ growth of Fe2O3 NPs, exhibiting high electrocatalytic activity for DA detection. [ABSTRACT FROM AUTHOR]

Dopamine is an excellent and flexible agent for surface coating of various materials, with the high-concentration of amine groups serving as a facile stabilizer for some metallic nanoparticles. In this work, mesoporous composites of nitrogen-doped carbon fibers (NCFs) decorated with cobalt nanoparticles have been successfully fabricated via the combination of a mussel-inspired biomimetic polydopamine (PDA)-coating process using electrospun porous polystyrene fibers as templates, a simple solution deposition method and subsequent high-temperature carbonization. This rationally designed porous NCF–Co composite possesses a large surface area and numerous electrochemically active sites, which exhibits synergistically improved catalytic activity for oxygen reduction reactions (ORRs) with a relatively positive onset potential, large current density, as well as superior durability compared with the commercial platinum–carbon (Pt/C) catalyst, making it a promising noble-metal-free catalyst for practical ORR applications. [ABSTRACT FROM AUTHOR]

Increasing energy demands and worsening environmental issues have stimulated intense research on alternative energy storage and conversion systems including supercapacitors and fuel cells. Here, a rationally designed hierarchical structure of ZnCo2O4@NiCo2O4 core-sheath nanowires synthesized through facile electrospinning combined with a simple co-precipitation method is proposed. The obtained core-sheath nanostructures consisting of mesoporous ZnCo2O4 nanowires as the core and uniformly distributed ultrathin NiCo2O4 nanosheets as the sheath, exhibit excellent electrochemical activity as bifunctional materials for supercapacitor electrodes and oxygen reduction reaction (ORR) catalysts. Compared with the single component of either ZnCo2O4 nanowires or NiCo2O4 nanosheets, the hierarchical ZnCo2O4@NiCo2O4 core-sheath nanowires demonstrate higher specific capacitance of 1476 F g−1 (1 A g−1) and better rate capability of 942 F g−1 (20 A g−1), while maintaining 98.9 % capacity after 2000 cycles at 10 A g−1. Meanwhile, the ZnCo2O4@NiCo2O4 core-sheath nanowires reveal comparable catalytic activity but superior stability and methanol tolerance over Pt/C as ORR catalyst. The impressive performance may originate from the unique hierarchical core-sheath structures that greatly facilitate enhanced reactivity, and faster ion and electron transfer. [ABSTRACT FROM AUTHOR]

Hydrogels, membrane distillation, solar desalination, wastewater treatment, water production Keywords: hydrogels; membrane distillation; solar desalination; wastewater treatment; water production EN hydrogels membrane distillation solar desalination wastewater treatment water production 1 1 1 05/12/21 20210510 NES 210510 In article number 2101036, Fei Zhao, Chenyang Zhao, Guihua Yu, and co-workers develop a hydrogel-based ultrathin membrane (HUM) for solar water purification. The HUM can synergistically coordinate facilitated vapor transfer and environmental energy harvesting in a solar-driven membrane distillation system, leading to a significant water yield improvement under one sun without any energy recycling and cooling accessories. [Extracted from the article]

The bio-inspired hierarchical “grape cluster” superstructure provides an effective integration of one-dimensional carbon nanofibers (CNF) with isolated carbonaceous nanoparticles into three-dimensional (3D) conductive frameworks for efficient electron and mass transfer. Herein, a 3D N-doped porous carbon electrocatalyst consisting of carbon nanofibers with grape-like N-doped hollow carbon particles (CNF@NC) has been prepared through a simple electrospinning strategy combined with in-situ growth and carbonization processes. Such a bio-inspired hierarchically organized conductive network largely facilitates both the mass diffusion and electron transfer during the oxygen reduction reactions (ORR). Therefore, the metal-free CNF@NC catalyst demonstrates superior catalytic activity with an absolute four-electron transfer mechanism, strong methanol tolerance and good long-term stability towards ORR in alkaline media. [ABSTRACT FROM AUTHOR]

The development of strong-yet-ductile polymer nanocomposites is critical, but still faces a great challenge. Herein, a hybrid carbon nanofiller consisting of one-dimensional carbon nanotube (CNT) and two-dimensional graphene (G) was molecularly engineered, and the as-prepared G-CNT hybrid nanofiller was then solution-casted with thermoplastic polyurethane (TPU) for the fabrication of TPU nanocomposite films. Due to the formation of unique network structure with multiple interactions of G-CNT hybrid within TPU matrices, the as-fabricated TPU nanocomposites showed simultaneously improved mechanical strength and toughness. With addition of only 1 wt% G-CNT hybrid, the tensile strength and toughness of TPU/(G-CNT) nanocomposite reached 69.5 MPa and 246.2 MJ m−3, 1.9 and 2.9 times over that of neat TPU, respectively. The significant and simultaneous enhancement in mechanical strength and toughness of TPU nanocomposites is attributed to homogeneously distributed G-CNT hybrid and its unique energy dissipations due to factures at different deformation stages upon tensile deformation. The work therefore provides a simple and efficient strategy for fabricating mechanically strong and ductile polymer nanocomposites with molecular-engineered hybrid carbon nanofillers. [ABSTRACT FROM AUTHOR]