With the rapid development of flexible electronic devices, current flexible energy storage devices face great challenge of achieving both high energy and power density. Exploiting ion capacitor is an intelligent way to improve the energy density without sacrificing the power density by utilizing the battery and capacitor-type energy storage mechanism. For the inspiration, a new flexible zinc-ion capacitor (FZIC) based on delta-MnO2@carbon cloth (delta-MnO2@CAC) battery-type cathode and MXene@cotton cloth (MXene@COC) capacitor-type anode has been designed and realized. The delta-MnO2@CAC//MXene@COC system in aqueous liquid electrolyte exhibits excellent electrochemical performance, e.g. a high energy density of 90 Wh kg(-1) (power density of 239 W kg(-1)) and a high power density of 3838 W kg(-1) (energy density of 26.8 Wh kg(-1)), a high capacitance retention of similar to 80.7% of its initial capacitance after 16,000 cycles and a high Coulomb efficiency of above 93.6% during all the cycles. Moreover, after being assembled by aqueous gel electrolyte, the FZIC also shows the superior electrochemical performance and excellent flexibility. This study of the FZIC provides an efficient way to develop the next-generation flexible energy storage devices with high performance.

Only two de novo biosynthetic routes to nicotinamide adenine dinucleotide (NAD + ) have been described, both of which start from a proteinogenic amino acid and are tightly controlled. Here we establish a C3N pathway starting from chorismate in Escherichia coli as a third NAD + de novo biosynthesis pathway. Significantly, the C3N pathway yielded extremely high cellular concentrations of NAD(H) in E. coli . Its utility in cofactor engineering was demonstrated by introducing the four-gene C3N module to cell factories to achieve higher production of 2,5-dimethylpyrazine and develop an efficient C3N-based whole-cell bioconversion system for preparing chiral amines. The wide distribution and abundance of chorismate in most kingdoms of life implies a general utility of the C3N pathway for modulating cellular levels of NAD(H) in versatile organisms.

Although current energy storage devices are limited by their own shortcomings, their merits such as superior power density and cycling stability for supercapacitors (SCs), and high energy density for batteries cannot be ignored either. Constructing hybrid SCs (HSCs) with capacitor-type electrodes and battery-type electrodes can combine the advantages of SCs and batteries. Herein, a zinc-ion HSC (ZHSC) is fabricated with a porous 3D MXene (Ti3C2Tx)-reduced graphene oxide aerogel cathode and zinc foil anode for the first time. As a result, the ZHSC exhibits excellent electrochemical performance with a high specific capacitance of 128.6 F g(-1) at a current density of 0.4 A g(-1) and a high energy density of 34.9 Wh kg(-1) at a power density of 279.9 W kg(-1). More importantly, after 75 000 charge and discharge cycles at a current density of 5 A g(-1), the capacitance retention is still above 95% of the initial capacitance. This work provides a new way of thinking for developing high-performance energy storage devices with superior energy, power density, and ultralong cycle life.

Correction for ‘High-performance alkaline hydrogen evolution electrocatalyzed by a Ni3N–CeO2 nanohybrid’ by Zhaomei Sun et al., Inorg. Chem. Front., 2018, 5, 3042–3045.

A trimeric porous coordination framework [Ni-3(TPTC)(IN)(2)(mu(2)-H2O)(2)(CH3OH)(2))](n)center dot x(solvents) (1, TPTC = terphenyl-3,3',5,5 "-tetracarboxylic acid, IN = isonicotinic acid) was synthesized and characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis, single-crystal and powder X-ray diffraction. It crystallizes in monoclinic space group C2/c with a = 33739(12), b = 14.820(5), c = 13.568(5) angstrom, beta = 97.388(6)degrees, V = 6728(4) angstrom(3) , Z = 4, M-r = 965.35, D-c = 0.953 g.cm(-3), F(000) = 1955.5, mu= 0.881 mm(-1), GOOF = 1.072, the final R = 0.0859 and wR = 0.2424 for 5284 observed reflections with I > 2 sigma(I). The structure of 1 is constructed from the linkage of trinuclear {Ni-3} second building units through TPTC and IN spacers, forming a 4,8-connected network of Schlafli symbol {3(2).4(2).5(2)}{3(4).4(6).5(8).6(8).7(2)}. The CO2 uptake values for 1 are 97.9 m(2).g(-1) at 273 K and 66.2 m(2).g(-1) at 298 K, while its N-2 adsorption values are 8.5 m(2).g(-1) at 273 K and 4.9 m(2).g(-1) at 298 K, respectively. These results show that 1 has high CO2 /N-2 adsorption selectivity at ambient conditions.

Correction for High-performance alkaline hydrogen evolution electrocatalyzed by a Ni3N-CeO2 nanohybrid' by Zhaomei Sun et al., Inorg. Chem. Front., 2018, 5, 3042-3045.

Anatase titania (TiO2) nanoparticles were synthesized via a self‐developed ethanol vapor‐thermal method at 240°C (T240) and 250°C (T250), i.e. at temperatures lower and higher, respectively, than the supercritical temperature (243.5°C, 7.0 MPa) of ethanol. Compared to T240, T250 exhibited a higher ratio of exposed (001) facets, oxygen vacancies, and concomitant TiOx. The specific surface area of T250 was 119.0 m2 g−1, smaller than that of T240 (144.2 m2 g−1). During the degradation of methylene blue, T250 exhibited a high apparent rate constant (Kapp) of 14.5 × 10−2 min−1, which was 6.3 times larger than that for T240. Furthermore, compared to T240, T250 exhibited better performance toward degradation of phenol. Results of electron spin resonance spectroscopy and photoluminescence indicated that the photogenerated electron–hole pairs possessed higher separation efficiency for T250 than for T240. In summary, the excellent photocatalytic performance of T250 originates from the higher ratios of exposed (001) facets, oxygen vacancies or TiOx, C═O groups adsorbed at the surface of particles, and higher separation efficiency of photogenerated electron–hole pairs. By employing this self‐developed vapor‐thermal method, a variety of catalysts and their composites can be synthesized, which may exhibit novel morphological characteristics and properties as well as excellent photocatalytic performance.

3-Phenyllactic acid (PLA) is an antimicrobial compound with broad-spectrum activity against bacteria and fungi that could be widely used in the food industry and livestock feeds. Notably, d-PLA exhibits higher antibacterial activity, which gains more attention than l-PLA. In this report, the d-lactate dehydrogenase DLDH744 from Sporolactobacillus inulinus CASD was engineered to increase the enzymatic activities toward phenylpyruvate by protein structure-guided modeling analysis. The phenylpyruvate molecule was first docked in the active center of DLDH744. The residues that might tightly pack around the benzene ring of phenylpyruvate were all selected for mutation. The single site mutant M307L showed the highest increased activity toward bulkier substrate phenylpyruvate than the wild type. By using the engineered d-lactate dehydrogenase M307L expressed in Escherichia coli strains, without coexpression of the cofactor regeneration system, 21.43 g/L d-PLA was produced from phenylpyruvate with a productivity of 1.58 g/L/h in the fed-batch biotransformation process, which ranked in the list as the highest production titer of d-PLA by d-lactate dehydrogenase. The enantiomeric excess value of produced d-PLA in the broth was higher than 99.7 %. Additionally, the structure-guided design of this enzyme will also provide referential information for further engineering other 2-hydroxyacid dehydrogenases, which are useful for a wide range of fine chemical synthesis.