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The development of self‐charging supercapacitor power cells (SCSPCs) has profound implications for smart electronic devices used in different fields. Here, we epitaxially electrodeposited Mo‐ and Fe‐codoped MnO2 films on piezoelectric ZnO nanoarrays (NAs) grown on the flexible carbon cloth (denoted ZnO@Mo‐Fe‐MnO2 NAs). A self‐charging supercapacitor power cell device was assembled with the Mo‐ and Fe‐codoped MnO2 nanoarray electrode and poly(vinylidenefluoride‐co‐trifluoroethylene) (PVDF‐Trfe) piezoelectric film doped with BaTiO3 (BTO) and carbon nanotubes (CNTs) (denoted PVDF‐Trfe/CNTs/BTO). The self‐charging supercapacitor power cell device exhibited an energy density of 30 μWh cm−2 with a high power density of 40 mW cm−2 and delivered an excellent self‐charging performance of 363 mV (10 N) driven by both the piezoelectric ZnO nanoarrays and the poly(vinylidenefluoride‐co‐trifluoroethylene) piezoelectric film doped with BaTiO3 and carbon nanotubes. More intriguingly, the device could also be self‐charged by 184 mV due to residual stress alone and showed excellent energy conversion efficiency and low self‐discharge rate. This work illustrates for the first time the self‐charging mechanism involving electrolyte ion migration driven by both electrodes and films. A comprehensive analysis strongly confirmed the important contribution of the piezoelectric ZnO nanoarrays in the self‐charging process of the self‐charging supercapacitor power cell device. This work provides novel directions and insights for the development of self‐charging supercapacitor power cells. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The kinetic process of a slow oxygen evolution reaction (OER) always constrains the efficiency of overall water electrolysis for H2 production. In particular, nonprecious metal electrodes for the OER have difficulty in possessing excellent electrocatalytic activity and stability in pH‐universal media simultaneously. In this work, urea is first used as a pore‐forming agent and active C/N source to fabricate a nanoporous NiFeCoCN medium‐entropy alloy (MEA) by high‐temperature sintering based on the nanoscale Kirkendall effect. The NiFeCoCN MEA achieves an overpotential of 432 mV at a current density of 10 mA·cm–2 and a lower Tafel slope of 52.4 mV·dec–1 compared to the IrO2/Ti electrode (58.6 mV·dec–1) in a 0.5 mol/L H2SO4 solution. In a 1 mol/L KOH solution, the NiFeCoCN MEA obtains an overpotential of 175 mV for 10 mA·cm–2 and a Tafel slope of 40.8 mV·dec–1, which is better than IrO2/Ni foam. This work proves a novel strategy to design and prepare nanoporous MEA materials with desirable C/N species, which provides promising prospects for the industrial production of H2 energy. [ABSTRACT FROM AUTHOR]

The 3,4‐dihydroxyphenylalanine (DOPA) melanin is one of the important virulence factors for Cryptococcus neoformans, which may trigger immune responses in the host. While the production of DOPA melanin is catalyzed by laccase that is predominantly encoded by LAC1 gene. Therefore, regulating the genetic expression of C. neoformans is conducive to exploring the impact of interested molecules on the host. In this work, we established two systems that were constructed quickly and easily for the knock‐down/knock‐out of LAC1 gene: RNA interference (RNAi) and clustered regularly interspaced short palindromic repeats CRISPR‐Cas9. The RNAi system was constructed by pSilencer 4.1‐CMV neo plasmid and short hairpin RNA to achieve effective transcriptional suppression. The CRISPR‐Cas9 system was used the PNK003 vectors to obtain a stable albino mutant strain. The results of phenotype, quantitative real‐time polymerase chain reaction, transmission electron microscope, and spectrophotometry were used to assess the ability of melanin production. As a result, the RNAi system displayed attenuation of transcriptional suppression when the transformants continuously passed on new plates. However, the transcriptional suppression of long loop in short hairpin RNA was more powerful and lasted longer. An albino strain produced by CRISPR‐Cas9 was completely unable to synthesize melanin. In conclusion, strains with different capacities of melanin production were obtained by RNAi and CRISPR‐Cas9 systems, which might be useful for exploring the linear relation between melanin and immunoreaction of the host. In addition, the two systems in this article might be convenient to quickly screen the possible trait‐regulating genes of other serotypes of C. neoformans. [ABSTRACT FROM AUTHOR]

Although MnO2 possesses many advantages, such as a high theoretical specific capacity, resource abundance, easy synthesis and environmental friendliness, its poor electrical conductivity and low utilization seriously hinder its large-scale application as an electrode in supercapacitors. A MnO2 and carbon nanotube (CNT) composite is co-deposited on flexible expanded graphite paper (EGP) by a facile method of composite brush plating. The three-dimensional conductive net of CNT in the composite greatly improves the supercapacitve and mechanical properties of MnO2 electrode. The paper mainly studied (i) the choice of composite brush plating voltage and (ii) the effect of the concentration of active substance CNTs deposited on the performance of supercapacitor. When the current density is 20 A g–1, the mass specific capacitance of the flexible CNT@MnO2/EGP electrode with an operation potential of 10 V in an electrolyte of 1.5 g L–1 CNTs dropped is 146 F g–1. The CNT@MnO2/EGP/active carbon (AC)/carbon fibre cloth (CFC) flexible aqueous asymmetric supercapacitor (ASC) exhibits an energy density of 36.3 Wh kg–1 at a power density of 126.2 W kg–1 and high cycling stability with 91% capacitance retention after 4000 cycles. This study paves the way to provide a simple and novel technique for the mass production of flexible MnO2 supercapacitor electrodes. The composite brush electroplating technology is successfully developed for fabricating flexible carbon nanotube@MnO2 composite co-deposited on expanded graphite paper, which displays excellent capacitive performance and cycling stability in an aqueous media. [ABSTRACT FROM AUTHOR]

With the emergence of intelligent society, high energy density and safety of flexible capacitive energy storage units are increasingly important in wearable devices. MnO2 as a flexible supercapacitor electrode material possesses the merits of high theoretical specific capacitance, low cost, and environmental friendliness. However, its poor conductivity, fragility, and low utilization hinder large-scale practical application. The rGO has excellent properties due to its unique sp2-hybridized carbon atom monolayer, such as high strength and high electrical conductivity. MnO2 can improve its own conductivity and specific capacitance by compounding with rGO. Both MnO2 and rGO can cooperate with each other to play their respective advantages and achieve a win-win situation. Herein, a facile brush electroplating technology is developed to fabricate flexible electrode materials composed of reduced-graphene oxide (rGO)@MnO2 composites grown on carbon cloth (CC) (denoted as rGO@MnO2/CC). A flexible rGO@MnO2/CC electrode prepared in an electrolyte with a rGO content of 1.0 g L−1 (denoted as 1.0-rGO@MnO2/CC) achieves high mass, area, and volume specific capacitances of 267 F g−1, 400 mF cm−2, and 13.3 F cm−3, respectively, at a charge–discharge rate of 0.25 A g−1. This is mainly due to the nanoporous structure formed by rGO and MnO2 nanosheets, which has higher electrical conductivity and good interfacial bonding. The rGO@MnO2/CC//active carbon (AC)/CC flexible aqueous asymmetric supercapacitor possesses a high energy density of 27.7 Wh kg−1 at a power density of 250 W kg−1 (0.9 mA cm−2) and a good capacitance retention of 76% after 10,000 charge–discharge cycles at a charge–discharge current density of 17.5 mA cm−2 (5 A g−1). This study provides a novel facile method for the large-scale fabrication of high-performance flexible aqueous supercapacitors. [ABSTRACT FROM AUTHOR]