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Electrochemical reduction of carbon dioxide (CO2) or carbon monoxide (CO) to valuable multi-carbon (C2+) products like acetate is a promising approach for a sustainable energy economy. However, it is still challenging to achieve high activity and selectivity for acetate production, especially in neutral electrolytes. Herein, a bioinspired hemin/Cu hybrid catalyst was developed to enhance the surface *CO coverage for highly efficient electroreduction of CO to acetate fuels. The hemin/Cu electrocatalyst exhibits a remarkable faradaic efficiency of 45.2% for CO-to-acetate electroreduction and a high acetate partial current density of 152.3 mA cm−2. Furthermore, the developed hybrid catalyst can operate stably at 200 mA cm−2 for 14.6 hours, producing concentrated acetate aqueous solutions (0.235 M, 2.1 wt%). The results of in situ Raman spectroscopy and theoretical calculations proved that the Fe–N4 structure of hemin could enhance the CO adsorption and enrich the local concentration of CO, thereby improving C–C coupling for acetate production. In addition, compared to the unmodified Cu catalysts, the Cu catalysts functionalized with cobalt phthalocyanine with a Co–N4 structure also exhibit improved acetate performance, proving the universality of this bioinspired molecule-enhanced strategy. This work paves a new way to designing bioinspired electrolysis systems for producing specific C2+ products from CO2 or CO electroreduction. [ABSTRACT FROM AUTHOR]

Design and fabrication of cost-effective (pre-)catalysts are important for water splitting and metal–air batteries. In this direction, various metal–organic frameworks (MOFs) have been investigated as pre-catalysts for oxygen evolution. However, the activation process and the complex reconstruction behaviour of these MOFs are not well understood. Herein, square-like MOF nanosheets in which carbon nanotubes were embedded were prepared by introducing an amine ligand to coordinate with Ni ions and then reacting with [Fe(CN)6]3−. The formed MOF nanosheets containing nickel and iron species were then activated by NaBH4, inducing the leaching of ligands and the formation of tiny active species in situ loaded on carbon nanotubes. The prepared catalyst shows superior oxygen evolution performance with an ultralow overpotential of 231 mV for 10 mA cm−2, a fast reaction kinetics with a small Tafel slope of 52.3 mV dec−1, and outstanding catalysis stability. The excellent electrocatalytic performance for oxygen evolution can be attributed to the structural advantage of in situ derived small sized active species and one-dimensional conductive networks. This work provides a new thought for the enhancement of the electrocatalytic performance of MOF materials. [ABSTRACT FROM AUTHOR]

The development of hydrogen–oxygen fuel cells with an alkaline electrolyte was highly limited by the sluggish kinetics of the hydrogen oxidation reaction (HOR). Here, with a pyrolysis-reduction route, a new RuNi-based electrocatalyst was prepared, which presents an ultrathin nanowire-like structure. In alkaline media, this catalyst shows an excellent catalytic performance with an exchange current density of 1.10 mA cm−2disk for hydrogen oxidation. The exchange current density and mass activity of this catalyst are much higher than those of its single-metal counterparts and even the commercial Pt/C catalyst containing 20% Pt. Such a remarkable catalytic activity can be explained by the interaction between Ru and Ni; the incorporation of Ni may induce an electronic effect on the optimization of the Ru–Had strength and provide a functional surface that can absorb OH species, thus boosting the catalytic activity. These findings may cast a new light on the exploration of low-cost but high-efficiency catalysts for fuel cells. [ABSTRACT FROM AUTHOR]

Metal nanoclusters (MeNCs), composed of a few to hundreds of metal atoms and appropriate surface ligands, have attracted extensive interest in the electrochemiluminescence (ECL) realm owing to their molecule-like optical, electronic, and physicochemical attributes and are strongly anticipated for discrete energy levels, fascinating electrocatalytic activity, and good biocompatibility. Over the past decade, huge efforts have been devoted to the synthesis, properties, and application research of ECL-related MeNCs, and this field is still a subject of heightened concern. Therefore, this perspective aims to provide a comprehensive overview of the recent advances of MeNCs in the ECL domain, mainly covering the emerged ECL available MeNCs, unique chemical and optical properties, and the general ECL mechanisms. Synthesis strategies for desirable ECL performance are further highlighted, and the resulting ECL sensing applications utilizing MeNCs as luminophores, quenchers, and substrates are discussed systematically. Finally, we anticipate the future prospects and challenges in the development of this area. [ABSTRACT FROM AUTHOR]

According to Hückel's and Baird's rules, cyclic species are generally aromatic only either in the lowest singlet state (S0) or in the lowest-lying triplet ππ* excited state (T1). Thus, species with aromaticity both in S0 and T1 states (termed as adaptive aromaticity) are particularly rare. Herein, we carry out density functional theory (DFT) calculations to examine the aromaticity of 16e metallapentalenes containing heteroatoms (N, O). Interestingly, metallazapentalenes show adaptive aromaticity whereas metalloxapentalenes display nonaromaticity in the S0 and T1 states, which is supported by structural, magnetic, and electronic indices. In addition, a series of metallazapentalenes containing strong σ- or π-donor ligands are predicted to achieve adaptive aromaticity. Our findings expand the family of adaptive aromatics significantly, inviting experimental chemists to realize more hetero-metallapentalenes with adaptive aromaticity. [ABSTRACT FROM AUTHOR]

As a fundamental concept in chemistry, aromaticity has been extended from traditional organics to organometallics. Similarly, hyperconjugative aromaticity (HCA) has also been developed from main group to transition metal systems through the hyperconjugation of the substituents. However, it remains unclear that how the oxidation state of transition metal in the substituents affects the HCA. Herein, we demonstrate via density functional theory calculations that HCA could disappear in indoliums when the Au(I) substituents are changed to the Au(III) ones. By tuning the ligand or cis–trans isomerization, HCA could be regained or enhanced in indoliums containing Au(III) substitutents. [ABSTRACT FROM AUTHOR]

In the past few decades, the construction of discrete supramolecular double-metallacycles has attracted wide interest because of their unique structures and their potential applications in photoelectric materials. Since some progress has been made in this area, it is time to summarize the progress of discrete supramolecular double-metallacycles. In this review, we will briefly introduce the synthetic strategy of discrete supramolecular double-metallacycles. In addition, we will discuss the design principles, preparation methods, optical properties, and functions of these discrete supramolecular double-metallacycles. [ABSTRACT FROM AUTHOR]

Disilene has attracted considerable interest due to the trans-bending geometry which is significantly different from the planar alkene. However, the equilibrium between disilene and isomeric silylsilylene has not been fully understood. Here, we report a density functional theory (DFT) study on this equilibrium. Calculations reveal significant effects of substituent, aromaticity and base. Specifically, the parent disilene is thermodynamically more stable than the isomeric silylene. When the methoxy substituent is introduced, the corresponding silylene becomes thermodynamically more stable, which could be rationalized by the Bent's rule. Interestingly, disilabenzene becomes thermodynamically more stable than the isomeric silylene when the concept of aromaticity is taken into account. Finally, once the base is introduced, the silylene could become thermodynamically more stable than the isomeric disilabenzene. The kinetic effect of the tautomerization with several typical substituents (F, Me and OMe) has also been investigated. Some species with a bridged form have been found to have a higher thermodynamic stability over the nonbridged ones. All these findings could be particularly useful to develop the chemistry of disilenes and silylenes. [ABSTRACT FROM AUTHOR]

Near-infrared photothermal-activated nanomaterials are emerging as a promising tool in precise cancer theranostics. This Frontier article highlights the recent advances of photothermal-activated nanoagents in biomedical applications, namely photothermal-initiated drug/contrast agent release, gene silencing, programmed targeting and gas theranostics. In the end, we give a perspective on the further development of photothermal-sensitive nanomedicines. [ABSTRACT FROM AUTHOR]

ZIF-67 derived CoP-decorated nitrogen-doped porous carbon (CoP-NPC) polyhedra anchored on reduced graphene oxide (RGO) sheets have been successfully prepared through an efficient pyrolysis–phosphidation–assembly strategy. The resulting CoP-NPC/RGO composite as an electrode for supercapacitors shows an enhanced electrochemical performance with high capacitances of 466.6 F g−1 at 1 A g−1 and 252 F g−1 at 20 A g−1, as well as 94.7% of capacitance retention after 10 000 cycles in 1 M H2SO4 solution. Moreover, the symmetrical two-electrode device assembled from CoP-NPC/RGO electrodes delivers a high energy density of 12 W h kg−1 at a power density of 500 W kg−1 and excellent long-term cycling stability (93% of the initial capacitance after 10 000 cycles at 10 A g−1). This superior electrochemical performance of CoP-NPC/RGO can be ascribed to its 3D interconnected porous structure and the synergistic effect between CoP and the nitrogen-doped carbon matrix. The unique architecture of the composites can effectively enhance the electrochemical performance by shortening the diffusion distance of electrolyte ions and improving the electrical conductivity and the contact area between active materials and the electrolyte. The excellent electrochemical performances make CoP-NPC/RGO a promising electrode material for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) nitrogen-doped carbon materials with a hierarchically porous structure are prepared by the introduction of nitrogen-doped carbon spheres (NCS) into the inter-sheet spaces of graphitic carbon nitride nanosheets (g-CN). The as-prepared graphitic carbon nitride/nitrogen-doped carbon sphere (g-CN/NCS) composites present a high nitrogen doping level, a unique hierarchically porous structure, and a high specific surface area of 448 m2 g−1. Such particular features make the g-CN/NCS composite an ideal material for supercapacitor electrodes, which could deliver a large specific capacitance of 403.6 F g−1 at 0.1 A g−1, an excellent rate capability of 220 F g−1 at 10 A g−1, and a high cycling stability with almost 100% capacitance retention after 5000 cycles at 20 A g−1. Furthermore, the g-CN/NCS electrode-based symmetric supercapacitors exhibit a decent energy density of 6.75 W h kg−1 at a power density of 1000 W kg−1. The enhanced performances are mainly attributed to the high nitrogen doping level and the hierarchically porous structure of the 3D structured g-CN/NCS composites, which provide an efficient pathway for transporting ions and electrons, and endow more active sites for electrochemical energy storage. [ABSTRACT FROM AUTHOR]

Metallaaromatics have attracted considerable interest from both experimentalists and theoreticians since the first prediction of metallabenzenes, in which a CH group is replaced by a transition metal fragment. In comparison with monocyclic metallabenzenes and bicyclic metallanaphthalenes, tricyclic metallaanthracenes are quite less developed. Thus, it is urgent to explore synthetic methods for this rare system. Here we report a thorough investigation on the formation of metallaanthracenes from transition metal fluorenyl complexes via density functional theory calculations. We systematically investigate how metal centres, ligands, and substituents affect such a rearrangement. Our results indicate that formation of metallaanthracenes could become thermodynamically and kinetically favourable from transition metal fluorenyl complexes by tuning suitable metal centres, ligands, and substituents, suggesting an unconventional facile way to prepare such rare tricyclic metallaaromatics for experimentalists, which is in sharp contrast to the traditional isomerisation of metallabenzenes to cyclopentadienyl complexes. [ABSTRACT FROM AUTHOR]

The first ruthenabenzothiophenes have been achieved via the C–H activation of thiophene. These species feature high thermal stability and resistance of a moderate oxidant, which constitute valuable addition to the rare metallaaromatic containing second-row transition metals. [ABSTRACT FROM AUTHOR]

A di-vanadium-substituted Lindqvist-type polyoxometalate [Cu(C12H8N2)2]2[V2W4O19]·4H2O (1) was hydrothermally synthesized and characterized structurally by single crystal X-ray diffraction analysis. X-ray photoelectron spectroscopy and energy disperse spectroscopy tests further prove the existence of vanadium. Ultraviolet photoelectron spectroscopy and density functional theoretical studies indicate that the energy level of 1 matches well with the conduction band of the TiO2. Furthermore, considering the semiconductor-like nature of 1 and the introduction of transition metal element Cu synchronously extends the absorption to the visible region, which should also be beneficial to the photovoltaic device performance. 1-Doped TiO2 composites (denoted as 1@TiO2) have been successfully fabricated by a simple sol–gel method, and introduced into the dye-sensitized solar cells (DSSCs) as co-sensitizers in N719-sensitized photoanodes by mixing 1@TiO2 with P25 nanoparticles with different weight ratios to enhance the photoelectric conversion efficiency. The investigations show that the DSSC assembled with 1@TiO2/19P25 photoanode has the best performance and the overall improvement of the efficiency is 21.6% compared with pure P25. Furthermore, the electrochemical impedance spectroscopy and open-circuit voltage decay investigations show that the cosensitization of 1 and N719 can promote electron transfer and restrain charge recombinations in the DSSCs, resulting in a longer electron lifetime. [ABSTRACT FROM AUTHOR]