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Solar-driven chemical processes are promising alternatives to conventional chemical production, especially considering the global challenges faced by humans, such as energy shortage, environmental pollution and global warming. Designing and constructing high-performance semiconductor photocatalysts with broad light absorption, matching band positions, fast carrier transfer, and sufficient active sites are highly desired but also challenging. Since bulk photocatalytic materials generally suffer from rapid carrier recombination due to their large physical dimensions, fabricating nanometer-sized photocatalytic materials is regarded as an effective strategy to shorten the carrier migration distance, thereby encouraging more carriers to be involved in photocatalytic reactions before recombination. 2D ultrathin materials are an important family of photocatalysts due to their large lateral dimension/thickness ratio. The goal of this review is to summarize the latest progress in 2D ultrathin materials from a green synthesis perspective, involving specific synthetic strategies and approaches. The discussed 2D materials include bismuth oxyhalides (BixOyXz), carbon nitrides (C3N4), conjugated covalent organic frameworks (COFs), and metal–organic frameworks (MOFs). [ABSTRACT FROM AUTHOR]

We report a bioinspired emulsion microreactor composed of an electrical double layer to mimic the functions of cell membranes. This "artificial cell" can modulate the phase-oriented transport of reagents at the oil–liquid interface via the electrical double layer, affording a powerful tool to optimize the selectivity in a catalytic reaction. [ABSTRACT FROM AUTHOR]

Developing active and stable electrocatalysts of earth-abundant elements towards the oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) still remains a crucial challenge. Herein, a cobalt-containing metal–organic framework using adenine as a ligand was synthesized and pyrolyzed without any other precursors, forming a cobalt nanoparticle-embedded nitrogen-doped carbon/carbon nanotube framework (Co@N-CNTF). Due to the abundant active sites of homogeneously distributed cobalt nanoparticles within nitrogen-doped graphitic layers, the resultant Co@N-CNTF catalysts exhibit an efficient and stable electrocatalytic performance as a tri-functional catalyst towards the ORR, OER and HER, including a high half-wave potential of 0.81 V vs. RHE for the ORR, and a low overpotential at 10 mA cm−2 for the OER (0.35 V) and HER (0.22 V). As a proof-of-concept, the Co@N-CNTF as an OER/HER bifunctional catalyst for full water splitting affords an alkaline electrolyzer with 10 mA cm−2 under a stable voltage of 1.71 V. Moreover, an integrated unit of a water-splitting electrolyzer using the Co@N-CNTF catalysts, which is powered with a rechargeable Zn–air battery using the Co@N-CNTF as an ORR/OER bifunctional catalyst on air electrodes, can operate under ambient conditions with high cycling stability, demonstrating the viability and efficiency of the self-powered water-splitting system. [ABSTRACT FROM AUTHOR]

Inspired by multi-scale structures mimicking Setaria viridis, herein, arrays of vertically aligned polyaniline (PANI) nanowires on MoO3/polypyrrole (PPy) core–shell nanobelts have been successfully synthesized via a two-step wet-chemistry strategy, including a simple in situ oxidative polymerization of pyrrole on MoO3 nanobelts, followed by an in situ oxidative polymerization of aniline on the MoO3/PPy core–shell nanobelts. By mimicking the hierarchically multi-scale topography of Setaria viridis for tailoring the nanostructures and functions of the electrode materials, in the resultant MoO3/PPy/PANI composites, the MoO3 nanobelt core acts as the “stalk” surrounded by conducting polymers, whereas the intermediate PPy functions as the buffer “grain” connecting the MoO3 and PANI nanowires, which provides good structural stability as well as an efficient electron transfer pathway. Moreover, the outermost PANI nanowire arrays act as the “bristles” allowing fast transport of ions and electrons between the electrodes. Due to their compositional and structural superiority, the as-obtained MoO3/PPy/PANI composites deliver excellent electrochemical energy storage performance including a high specific capacitance of 1315 F g−1 at 0.5 A g−1, a high energy density of 63 W h kg−1 and an excellent cycling stability (capacitance retention of 86% at 10 A g−1 after 20 000 cycles). The easy synthesis and excellent electrode performance of the MoO3/PPy/PANI composites make them attractive candidates as promising electrode materials for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

In the past few years, Ni(OH)2 has been found to be an effective cocatalyst for photocatalytic hydrogen evolution. Herein, we report that it can also be used to enhance the photoreduction of CO2 into chemical fuels. Vertically aligned Ni(OH)2 nanosheets are deposited onto electrospinning TiO2 nanofibers via simple wet-chemical precipitation to manufacture TiO2/Ni(OH)2 hybrid photocatalysts. The TiO2 nanofibers can direct the ordered growth of Ni(OH)2 nanosheets, which have a thickness of 20 nm and uniformly cover the surface of the TiO2 substrate. The TiO2/Ni(OH)2 hierarchical composite displays remarkably improved photocatalytic CO2 reduction activity compared to that displayed by pristine TiO2 fibers. The bare TiO2 can only produce methane and carbon monoxide (1.13 and 0.76 μmol h−1 g−1, respectively) upon CO2 photoreduction. After loading 0.5 wt% Ni(OH)2, the methane yield increases to 2.20 μmol h−1 g−1, meanwhile the CO yield is unchanged. Interestingly, alcohols (methanol and ethanol) also appear as products, in addition to CH4 and CO, over the TiO2/Ni(OH)2 hybrid, and the maximum yield is reached with 15 wt% Ni(OH)2 loading (0.58 and 0.37 μmol h−1 g−1 for methanol and ethanol, respectively). This can be ascribed to an enhanced charge separation efficiency and higher CO2 capture capacity due to the presence of Ni(OH)2. These results demonstrate that Ni(OH)2 can not only improve the total CO2 conversion efficiency, but can also alter the product selectivity upon photocatalysis. This work opens a new pathway for achieving high-efficiency photocatalytic CO2 reduction with Ni(OH)2 as a cocatalyst. [ABSTRACT FROM AUTHOR]

The rational design and scalable synthesis of hierarchical porous carbon as an electrode material for high-energy-density supercapacitors has drawn wide interest. Herein, we report an environmentally friendly one-pot strategy for the synthesis of interwoven carbon nanotube (CNT)/carbon nanosheet (CNS) sandwiches in a molten salt. Green and cheap biomass glucose was chosen as the precursor for producing CNSs at a pyrolysis temperature of 700 °C in a conventional inorganic salt mixture (LiCl and KCl eutectic), while commercially available CNTs were introduced as veins sandwiched with CNS laminae. Relying on the compositional and structural superiorities benefitting from mimicking net-veined leaves, the unique CNT/CNS sandwiches manifest excellent electrochemical capacitive performance in terms of high specific energy (23.6 W h kg−1), excellent rate capacitance retention (∼75% at 10 A g−1) and exceptional cycling stability (capacitance retention of ∼100% after 5000 cycles). [ABSTRACT FROM AUTHOR]

Claisen-Schmidt (CS) condensation between acetone and benzaldehyde with NaOH as the catalyst is a well-recognized pathway for the synthesis of benzalacetone (BA). However, this process is compromised by a side reaction, i.e. , a second CS reaction between benzaldehyde and the BA product. In this work, we designed a stirring-induced emulsion synthesis technique for the cyclic and scaling-up production of BA with 99 ± 1% selectivity, without the use of surfactants. In this approach, the water-soluble acetone and NaOH were separated from the oil-soluble benzaldehyde by the organic-aqueous phase interface, such that the CS condensation could only be executed at the liquid interface. The just-formed BA molecules diffuse to the interior of the oil solvent, where any subsequent CS post-reaction is rendered negligible, owing to the absence of NaOH. The oil phase containing the BA molecules can be easily separated from the aqueous solution by stopping stirring and undisturbed standing, allowing for a large-scale production protocol. As a proof of concept, over 1 kg of BA was produced in the laboratory with high yield and purity., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)