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Amorphous chromium oxide confined Ni/NiO nanoparticles-assembled nanosheets are designed for highly efficient and stable overall urea splitting. [Display omitted] Applications of urea oxidation reaction (UOR) in various sustainable energy-conversion systems are greatly hindered by its slow kinetics. Herein, we demonstrate an in - situ confined synthesis method that produces amorphous chromium oxide confined Ni/NiO nanoparticles-assembled nanosheets (Ni/NiO@CrO x) with fast reaction kinetics towards UOR. The confinement effect of the in - situ generated CrO x overlay contributes to ultrafine Ni/NiO nanoparticles, bringing about rich Ni/NiO and NiO/CrO x interfaces. In - situ Raman and electrochemical characterization show that both CrO x and metallic Ni can promote the formation of the NiOOH species and the electron transfer, leading to high intrinsic activity and fast reaction kinetics. At 1.40 V vs. reversible hydrogen electrode, the Ni/NiO@CrO x delivers a current density of 275 mA cm−2, which is about 2.6 and 6.1 times as large as those of the NiO@CrO x and NiO, respectively. In addition, the protective effect of the CrO x overlay leads to robust working stability towards UOR. Further, the Ni/NiO@CrO x nanosheets are used as bifunctional catalysts for overall urea splitting, and a small electrolysis cell voltage of 1.44 V is needed to reach the benchmark current density of 10 mA cm−2. [ABSTRACT FROM AUTHOR]

The bulk Ni/Fe ratio is a crucial parameter that determines the catalytic performance of the NiFe alloys by affecting the surface Fe/Ni ratio and the oxygen vacancy (O V) content, and the Ni 4 Fe 1 alloy with well-tailored oxide/metal interface presents highly enhanced oxygen evolution reaction with an overpotential of 242 mV at 10 mA cm−2 and a small Tafel slope of 37 mV dec−1. [Display omitted] NiFe alloys are among the most promising electrocatalysts for oxygen evolution reaction (OER). However, a comprehensive study is yet to be done to reveal the surface structure-performance relationship of NiFe alloys. In particular, the role of the ultrathin surface oxide layer, which is unavoidable for pure NiFe alloys, is always neglected. Herein, a series of NiFe alloys with different Ni/Fe ratios are fabricated. It is found that different Ni/Fe ratios lead to significant differences in surface composition and structure of the NiFe alloys, and thus affect their catalytic performance. Then, the oxide/metal interface of the Ni 4 Fe 1 alloy is tailored by adjusting the hydrogenation temperature to further understand the surface structure-activity relationship, and the optimal OER performance is achieved at the oxide/metal interfaces that have suitable surface Fe/Ni ratio and an appropriate amount of oxygen vacancies. In - situ Raman characterization shows that the Ni 4 Fe 1 alloy with well-tailored oxide/metal interface facilitates the formation of active species. Density functional theory calculations demonstrate that the ultrathin surface oxide layers are responsible for the high catalytic activity of the NiFe alloys, and that the quantity of oxygen vacancies in the surface oxides affects the adsorption energy of O* and thus to a great extent determines the catalytic activity. [ABSTRACT FROM AUTHOR]

Intercalation-induced partial exfoliation of NiFe LDHs with tunable interlayer space has been achieved by a scalable synthesis method, and the optimal NiFe LDHs show an overpotential of 225 mV at 10 mA cm−2 and a small Tafel slope of 43 mA dec−1. [Display omitted] Edge sites and interlayer space of NiFe layered double hydroxides (LDHs) play an important role in water oxidation. However, the combined effect of interlayer expansion and partial exfoliation on the catalytic activity is yet to be investigated. Herein, scalable synthesis of partially exfoliated citrate-intercalated NiFe LDHs with tunable interlayer space have been achieved. The effect of citrate concentration on the phase, morphology, surface elemental composition, electronic states of surface metals, and electrochemical properties are comprehensively studied. The unique structure results in improved intrinsic catalytic activity and abundant active edge sites for oxygen evolution reaction. The optimal NiFe LDHs show an overpotential of 225 mV at 10 mA cm−2, which is much smaller than that (∼305 mV) of the single-layer NiFe LDH nanosheets reported in the literature. The high catalytic activity can be mainly attributed to the combined effect between the enlarged interlayer space and the partial exfoliation/nanosheet thickness. That is, the interlayer space is related to the reaction kinetics/mechanism, while the degree of exfoliation affects the magnitude of the current density at a certain potential. [ABSTRACT FROM AUTHOR]

Metal organic frameworks derived NiCo hydroxides with abundant Ni3+ species and surface oxalate ligand are synthesized for highly enhanced electrochemical glycerol oxidation reaction. [Display omitted] Glycerol oxidation reaction can be substituted for oxygen evolution reaction for more efficient hydrogen production due to its lower thermodynamic potential. Herein, a series of NiCo hydroxide nanosheets containing abundant Ni3+ species and surface ligands were synthesized by in - situ structural transformation of bimetallic organic frameworks in alkaline media for efficient glycerol oxidation reaction. It is found that the incorporation of Co ions increases the content of the Ni3+ species, and that the Ni/Co ratio of 1.0 lead to the optimal catalytic performance. The oxalate-modified nickel–cobalt hydroxide with the optimized Ni/Co ratio can deliver a current density of 10 mA cm−2 at 1.26 V vs. RHE (reversible hydrogen electrode), and reaches its maximum selectivity and Faradaic efficiency at 1.30 V vs. RHE. A high selectivity of 82.9% and a Faradaic efficiency of 91.0% are achieved. The high catalytic activity can be mainly attributed to the abundant Ni3+ species and surface carboxyl groups. [ABSTRACT FROM AUTHOR]

Cities worldwide are facing a significant threat of stormwater hazards caused by the increase in extreme downpours and urbanization. Meso-level urban stormwater management focuses on alleviating the detrimental impacts of urban flooding and enhancing water resource utilization at the block or community scale, typically through 1) specific policies and management rules; 2) catchment-scale scenario simulation, optimization and evaluation; 3) the group of stormwater control measures implementation. It may effectively coordinate macro-level urban stormwater management planning and micro-level distributed stormwater control facilities. This study conducts a review of Urban Stormwater Management at Meso-level (USM-M) with a view to research publication trends, citation analysis, geographic spread and subject category, as well as content analysis, including temporal progression and research gaps. The Web of Science database and CiteSpace are used for the bibliometric analysis of 66 articles from 2006 to 2021. The results show that the number of USM-M topic articles generally has an upward trend over the years. Whilst the United States and China are leading research on this topic, the European countries have diverse local research and dense cooperation. Research foci have generally shifted from theoretical frameworks to multi-element subdivided topics and specific technical roadmaps. Moreover, the spatial layout optimization and multi-functional integration are, or will be, potential research directions in terms of enhancing stormwater utilization and co-benefits of USM-M. This systematic review concludes trends, challenges and potential approaches of USM-M, and aims to provide recommendations for researchers and policymakers on the development of a more advanced and comprehensive USM-M. • This paper aims to quantitatively and qualitatively review how Urban Stormwater Management at Meso-level (USM-M) is being studied and applied. • The question was "What are the trends, challenges and approaches of USM-M research?". • USM-M is applied at the catchment, block, community scale, and play a coordinator role between macro-level and micro-level. • Research focus has shifted from theoretical frameworks to subdivided topics and specific technical roadmaps. • Optimal spatial layout and multi-functional integration of USM-M implementation are potential directions. [ABSTRACT FROM AUTHOR]

Previous studies in our laboratory discovered that SIX1 mRNA expression increased during in vitro progression of HPV16-immortalized human keratinocytes (HKc/HPV16) toward a differentiation-resistant (HKc/DR) phenotype. In this study, we explored the role of Six1 at early stages of HPV16-mediated transformation by overexpressing Six1 in HKc/HPV16. We found that Six1 overexpression in HKc/HPV16 increased cell proliferation and promoted cell migration and invasion by inducing epithelial–mesenchymal transition (EMT). Moreover, the overexpression of Six1 in HKc/HPV16 resulted in resistance to serum and calcium-induced differentiation, which is the hallmark of the HKc/DR phenotype. Activation of MAPK in HKc/HPV16 overexpressing Six1 is linked to resistance to calcium-induced differentiation. In conclusion, this study determined that Six1 overexpression resulted in differentiation resistance and promoted EMT at early stages of HPV16-mediated transformation of human keratinocytes. [ABSTRACT FROM AUTHOR]

The introduction of a surface ethylenediaminetetraacetate-metal coordination layer activates the Ni x Fe 3-x O 4 as an outstanding electrocatalyst for oxygen evolution reaction, exhibiting a very small overpotential of 180 mV at 10 mA cm−2 and excellent working durability. [Display omitted] Nickel-iron oxides are competitive electrocatalysts for oxygen evolution reaction, but their practical applications are restricted by the less-than-desirable intrinsic activity and working stability. To tackle the challenge, surface coordination chemistry is applied to the nickel–iron oxides through a complex-assisted in - situ crystal growth strategy. The ethylenediaminetetraacetate (EDTA) coordinated Ni x Fe 3-x O 4 (Ni x Fe 3-x O 4 -EDTA) is prepared by a simple one-pot hydrothermal process. The coordinated EDTA molecules can deeply alter the surface coordination structure of the Ni x Fe 3-x O 4. The Ni x Fe 3-x O 4 -EDTA demonstrates outstanding intrinsic activity towards oxygen evolution reaction, requiring only a small overpotential of 180 mV to reach 10 mA cm−2 in 1.0 M KOH. Moreover, the Ni x Fe 3-x O 4 -EDTA exhibits extremely stable long-term working stability. Density functional theory calculations show that the highly enhanced intrinsic activity is attributed to the surface coordinated EDTA-induced favorable electronic structure and coordination environment, which tunes the adsorption strength of the intermediates and optimizes the energetics of the elementary steps, while the high stability is ascribed to the strong coordination ability of EDTA. [ABSTRACT FROM AUTHOR]

A novel MOF-assisted in - situ synthetic strategy is developed to fabricate NiOOH-rich bimetallic catalysts for highly efficient urea oxidation reaction. [Display omitted] NiOOH has been considered as the active center for urea oxidation reaction (UOR), but it remains challenging to synthesize high-performance NiOOH-based catalysts. Herein, we realize the synthesis of a high-performance NiOOH-based catalyst through in - situ transformation from the NiMn-based metal–organic framework to NiMnOOH. X-ray photoelectron spectroscopy characterization shows that the Ni3+/Ni2+ ratio in the NiMnOOH is 3.9 times as big as that in the Ni(OH) 2 , and in - situ Raman characterization further consolidates the presence of the NiOOH species in the NiMnOOH and as well unveils the faciliated Ni2+/Ni3+ redox reaction. The abundant NiOOH species, the markedly facilitated Ni2+/Ni3+ redox reaction and the Ni-Mn synergy contribute to the high intrinsic activity of the NiMnOOH towards UOR. The NiMnOOH exhibits an impressively low onset potential of 1.305 V vs reversible hydrogen electrode (RHE) and requires only a small potential of 1.34 V vs RHE to deliver a current density of 100 mA cm−2 in 1.0 M KOH + 0.33 M urea. In addition, the NiMnOOH catalyst possesses good long-term working stability. [ABSTRACT FROM AUTHOR]