The development of high‐performance oxygen reduction reaction (ORR) catalysts derived from non‐Pt group metals (non‐PGMs) is urgent for the wide applications of proton exchange membrane fuel cells ...(PEMFCs). In this work, a facile and cost‐efficient supramolecular route is developed for making non‐PGM ORR catalyst with atomically dispersed Fe‐Nx/C sites through pyrolyzing the metal‐organic polymer coordinative hydrogel formed between Fe3+ and α‐L‐guluronate blocks of sodium alginate (SA). High‐angle annular dark field scanning transmission electron microscopy (HAADF‐STEM) and X‐ray absorption spectroscopy (XAS) verify that Fe atoms achieve atomic‐level dispersion on the obtained SA‐Fe‐N nanosheets and a possible fourfold coordination with N atoms. The best‐performing SA‐Fe‐N catalyst exhibits excellent ORR activity with half‐wave potential (E1/2) of 0.812 and 0.910 V versus the reversible hydrogen electrode (RHE) in 0.5 m H2SO4 and 0.1 m KOH, respectively, along with respectable durability. Such performance surpasses that of most reported non‐PGM ORR catalysts. Density functional theory calculations suggest that the relieved passivation effect of OH* on Fe‐N4/C structure leads to its superior ORR activity to Pt/C in alkaline solution. The work demonstrates a novel strategy for developing high‐performance non‐PGM ORR electrocatalysts with atomically dispersed and stable M‐Nx coordination sites in both acidic and alkaline media.
A novel non‐Pt group metal oxygen reduction reaction (non‐PGM ORR) catalyst with atomically dispersed Fe‐Nx/C sites is developed through a metal‐organic polymer supramolecule strategy. The pH‐universal catalyst delivers extraordinarily high ORR activity and stability. Theoretical calculations suggest that the relieved passivation effect of OH* on Fe‐N4/C structure leads to its superior ORR activity to Pt/C in alkaline solution.
Internet addiction has been found to be prevalent worldwide, including Asian countries, and related to several negative outcomes and other behavioral addictions. The Bergen Social Media Addiction ...Scale (BSMAS), Smartphone Application-Based Addiction Scale (SABAS), and nine-item Internet Gaming Disorder Scale-Short Form (IGDS-SF9) have been extensively used to assess internet-related addictions. However, the three aforementioned instruments have rarely been used in Asian countries. The aim of the present study was to investigate whether the BSMAS, SABAS, and IGDS-SF9 were appropriate for use in heterogeneous subsamples from Hong Kong and Taiwan. University students from Hong Kong (n = 306) and Taiwan (n = 336) were recruited via an online survey. Multigroup confirmatory factor analysis (MGCFA) was used to assess measurement invariance of the BSMAS, SABAS, and IGDS-SF9 across the two subcultures. The original unidimensional structures of BSMAS, SABAS and IGDS-SF9 were confirmed through confirmatory factorial analysis in both subcultures. The MGCFA results showed that the unidimensional structures of the BSMAS and IGDS-SF9 were invariant across the two Chinese cultural areas (Hong Kong and Taiwan). However, the measurement invariance of the SABAS was established after some model modifications. In conclusion, the present study found that the Chinese BSMAS, SABAS, and IGDS-SF9 were all adequate instruments to validly assess internet-related addictions among university students. The three brief instruments used for assessing addictions to social media, smartphone applications, and online gaming are valid and psychometrically robust across two Chinese subcultures and can be used by healthcare professionals in these regions.
•Chinese Bergen Social Media Addiction Scale has unidimensional structure.•Chinese Smartphone Application-Based Addiction Scale has unidimensional structure.•Chinese Internet Gaming Disorder Scale-Short Form has unidimensional structure.
Electrochemical reduction of carbon dioxide (CO2RR) into value‐added chemicals is a promising tactic to mitigate global warming. However, this process resists catalyst preparation, low faradaic ...efficiency (FE%) towards multi‐carbon products, and insights into mechanistic understanding. Indeed, it is demonstrated that this Fe single‐atom catalyst (Fe SAC) exists in three oxygen coordination of Fe–(O)3 configuration in Nafion coated functionalized multi‐wall carbon nanotubes (Fe‐n‐f‐CNTs), which is obtained via a simple ionic exchange method under ambient conditions. The electrochemical performance reveals that Fe SACs achieve an FE of 45% and a yield rate of 56.42 µmol cm−2 h−1 at −0.8 VRHE for ethanol. In situ X‐ray analysis reveals that the Fe SACs have variable electronic states and keeps close +3 of the oxidation state at the potential range of CO2RR. The catalytic feature reduces the reaction energy and induces the electrons transferred to the adsorbed products intermediates of *COOH and *OCHO, thus promoting CO. The carboxylic functional group on the CNTs stabilizes the Fe active sites via electrostatic interaction, verified by density functional theory calculations. The yield rate of Fe SACs indicates that the Fe single‐atom site can instantly provide a large CO to help conversion of CO2‐to‐C2 product on the CNTs.
The Fe–(O)3 single‐atom catalyst synthesis via a simple ionic exchange method on Nafion‐coated functionalized multi‐wall carbon nanotubes (Fe‐n‐f‐CNTs). The Fe SACs and functionalized CNTs are dual active sites toward CO2RR with enhanced selectivity of C2 products. During CO2RR, the carboxylic functional group stabilizes the Fe single‐atom active catalytic site via electrostatic interactions.
The will to circumvent capacity fading, Li dendrite formation, and low coulombic efficiency in anode-free Li-metal batteries (AFLMBs) requires a radical change in the science underpinning new ...materials discovery, battery design, and understanding electrode interfaces. Herein, a Cu current collector formed with ultrathin multilayer graphene grown via chemical vapor deposition (CVD) was used as an artificial layer to stabilize the electrode interface and sandwich-deposited Li with Cu. A multilayer graphene film's superior strength, chemical stability, and flexibility make it an excellent choice to modify a Cu electrode. Fabricating an anode bigger than the cathode improved the alignment of the electrodes during assembly, minimizing interfacial stress. Here, 19 mm electrodes when paired with a commercial LiFePO4 cathode (mass loading: ∼12 mg cm-2) delivered the first-cycle discharge capacities of 147 and 151 mA h g-1 for bare and multilayer-graphene-protected electrodes, respectively, which could alleviate the big hurdle (initial capacity loss) in anode-free batteries. After 100 round-trip cycles, bare Cu and multilayer-graphene-protected electrodes retained ∼46 and ∼61% of their initial capacities, respectively, in an ether-based electrolyte at the rate of 0.1 C.
Given the many technological advances over the past two decades, a small minority of young people are at risk of problematic use or becoming addicted to these technologies (including activities on ...the internet and smartphones). Many brief psychometric scales have been developed to assess those at risk of problematic use or addiction including the six-item Smartphone Application-Based Addiction Scale SABAS, the six-item Bergen Social Media Addiction Scale BSMAS, and the nine-item Internet Gaming Disorder Scale-Short Form IGDS-SF9). However, to date, the reproducibility of these three scales has only been examined over a short period of time (e.g., two weeks), and it is unclear whether they are time invariant across a longer period (e.g., three months). Given the emergence of internet and smartphone addiction in Chinese population, the present study translated the three instruments into Chinese and recruited 640 university students (304 from Hong Kong 99 males and 336 from Taiwan 167 males) to complete the three scales twice (baseline and three months after baseline). Multigroup confirmatory factor analysis (MGCFA) was applied to examine the time invariance. The intraclass correlation coefficient (ICC) was used to assess the relative reliability, and the percentage of smallest real difference (SRD%) was utilized to explore the absolute reliability for the three scales. MGCFA showed that all three scales were time invariant across three months. ICC demonstrated that all the scales were satisfactory in reproducibility (0.82 to 0.94), and SRD% indicated that all the scales had acceptable measurement noise (23.8 to 29.4). In conclusion, the short, valid, reliable, and easy-to-use Chinese SABAS, BSMAS, and IGDS-SF9 show good properties across periods of three months.
•Smartphone addiction, social media addiction, and internet gaming disorder are specific internet-related disorders.•Psychometrically robust instruments have been developed for these specific disorders.•The reproducibility of these scales has only been examined over a short period of time.•Time invariance of three scales were tested over a 3-month period.•The three scales had satisfactory reproducibility with little measurement noise.
Electrochemical energy storage and conversion devices play a key role in the development of clean, sustainable, and efficient energy systems to meet the sustainable growth of our society. However, ...challenging issues including the sluggish kinetics of oxygen electrode reactions involving the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) are present, limiting the implementation of devices such as metal‐air batteries, water electrolyzers, and regenerative fuel cells. In this review, various monometallic and bimetallic transition metal oxides (TMOs) and hydroxides are summarized in terms of their application for ORR/OER, in which the merits and demerits of various precious metal and carbon‐based metal oxide materials are discussed, with requirements for better electrocatalysts and catalyst support being introduced as well. Following this, different approaches to improve catalytic activity such as the introduction of doping and defects, the manipulation of crystal facets, and the engineering of supports, compositions, and morphologies are summarized in which TMOs with improved ORR/OER catalytic activities can be synthesized, further improving the speed, stability, and polarization of electrochemical energy storage and conversion devices. Finally, perspectives into the improvement of performance and the better understanding of ORR/OER mechanisms for bifunctional electrocatalysts using in situ spectroscopic techniques and density functional theory calculations are also discussed.
It is important to design and enhance activity and stability of bifunctional electrocatalyst. In order to improve both activity and stability, doping engineering, morphology and compositional engineering, defect engineering, support engineering, and crystal facet engineering are most important factors.
Herein, we report hierarchical 3D NiMn-layered double hydroxide (NiMn-LDHs) shells grown on conductive silver nanowire (Ag NWs) cores as efficient, low-cost, and durable oxygen reduction reaction ...(ORR)/oxygen evolution reaction (OER) bifunctional electrocatalysts for metal–air batteries. The hierarchical 3D architectured Ag NW@NiMn-LDH catalysts exhibit superb OER/ORR activities in alkaline conditions. The outstanding bifunctional activities of Ag NW@NiMn-LDHs are essentially attributed to increasing both site activity and site populations. The synergistic contributions from the hierarchical 3D open-pore structure of the LDH shells, improved electrical conductivity, and small thickness of the LDHs shells are associated with more accessible site populations. Moreover, the charge transfer between Ag cores and metals of LDH shells and the formation of defective and distorted sites (less coordinated Ni and Mn sites) strongly enhance the site activity. Thus, Ag NW@NiMn-LDH hybrids exhibit a 0.75 V overvoltage difference between ORR and OER with excellent durability for 30 h, demonstrating the distinguished bifunctional electrocatalyst reported to date. Interestingly, the homemade rechargeable Zn–air battery using the hybrid Ag NW@NiMn-LDHs (1:2) catalyst as the air electrode exhibits a charge–discharge voltage gap of ∼0.77 V at 10 mA cm–2 and shows excellent cycling stability. Thus, the concept of the hierarchical 3D architecture of Ag NW@NiMn-LDHs considerably advances the practice of LDHs toward metal–air batteries and oxygen electrocatalysts.
Rechargeable aqueous zinc-ion batteries (ZIBs) are emerging as an alternative to lithium-ion batteries in large-scale energy storage applications due to their safety and environmental friendliness. ...However, their application is hindered by the lack of suitable cathode materials that provide high capacity and long cycling stability. In this work, we have designed Cu-MnO nanospheres with abundant manganese/oxygen defects as a cathode material
via
calcination and reduction of manganese dioxide (MnO
2
) in an Ar/H
2
atmosphere. Investigation of the electrochemical mechanism showed that the spinel-type Cu-MnO electrode started to transform into layered-type Cu-MnO
2
·
n
H
2
O nanoflowers upon initial charging, and thus, the subsequent Zn
2+
intercalation and H
+
conversion reactions took place in the Cu-MnO
2
·
n
H
2
O material. The underlying phase transformation of the Cu-MnO nanospheres and energy storage mechanism of the Cu-MnO
2
·
n
H
2
O nanoflowers were systematically investigated using a broad range of characterization techniques. Manganese vacancy was also observed in Cu-MnO
2
·
n
H
2
O, which interestingly triggered the lattice oxygen redox reaction. As a result, when employed as a cathode material in zinc-ion batteries, Cu-MnO
2
·
n
H
2
O delivered a high specific capacity of 320 mA h g
−1
and long-term cycling stability with a capacity retention of over 70% after 1000 cycles. This work not only provides insight into the design of transition-metal-modified manganese monoxide cathodes but also broadens the horizon for understanding the electrochemical properties and energy-storage mechanism of low-valance manganese-based cathode materials in rechargeable zinc-ion batteries.
Rechargeable aqueous zinc-ion batteries (ZIBs) are emerging as an alternative to lithium-ion batteries in large-scale energy storage applications due to their safety and environmental friendliness.
Organometal halide perovskite solar cells have evolved in an exponential manner in the two key areas of efficiency and stability. The power conversion efficiency (PCE) reached 20.1% late last year. ...The key disquiet was stability, which has been limiting practical application, but now the state of the art is promising, being measured in thousands of hours. These improvements have been achieved through the application of different materials, interfaces and device architecture optimizations, especially after the investigation of hole conductor free mesoporous devices incorporating carbon electrodes, which promise stable, low cost and easy device fabrication methods. However, this work is still far from complete. There are various issues associated with the degradation of Omh-perovskite, and the interface and device instability which must be addressed to achieve good reproducibility and long lifetimes for Omh-PSCs with high conversion efficiencies. A comprehensive understanding of these issues is required to achieve breakthroughs in stability and practical outdoor applications of Omh-PSCs. For successful small and large scale applications, besides the improvement of the PCE, the stability of Omh-PSCs has to be improved. The causes of failure and associated mechanisms of device degradation, followed by the origins of degradation, approaches to improve stability, and methods and protocols are discussed in detail and form the main focus of this review article.
What are the bottlenecks for organometal halide perovskite solar cells to achieve the stability required for commercialization?
Abstract
The development of high‐performance oxygen reduction reaction (ORR) catalysts derived from non‐Pt group metals (non‐PGMs) is urgent for the wide applications of proton exchange membrane fuel ...cells (PEMFCs). In this work, a facile and cost‐efficient supramolecular route is developed for making non‐PGM ORR catalyst with atomically dispersed Fe‐N
x
/C sites through pyrolyzing the metal‐organic polymer coordinative hydrogel formed between Fe
3+
and α‐L‐guluronate blocks of sodium alginate (SA). High‐angle annular dark field scanning transmission electron microscopy (HAADF‐STEM) and X‐ray absorption spectroscopy (XAS) verify that Fe atoms achieve atomic‐level dispersion on the obtained SA‐Fe‐N nanosheets and a possible fourfold coordination with N atoms. The best‐performing SA‐Fe‐N catalyst exhibits excellent ORR activity with half‐wave potential (
E
1/2
) of 0.812 and 0.910 V versus the reversible hydrogen electrode (RHE) in 0.5
m
H
2
SO
4
and 0.1
m
KOH, respectively, along with respectable durability. Such performance surpasses that of most reported non‐PGM ORR catalysts. Density functional theory calculations suggest that the relieved passivation effect of OH* on Fe‐N
4
/C structure leads to its superior ORR activity to Pt/C in alkaline solution. The work demonstrates a novel strategy for developing high‐performance non‐PGM ORR electrocatalysts with atomically dispersed and stable M‐N
x
coordination sites in both acidic and alkaline media.
PDF
