A novel in situ replication and polymerization strategy is developed for the synthesis of Fe‐N‐doped mesoporous carbon microspheres (Fe‐NMCSs). This material benefits from the synergy between the ...high catalytic activity of Fe‐N‐C and the fast mass transport of the mesoporous microsphere structure. Compared to commercial Pt/C catalysts, the Fe‐NMCSs show a much better electrocatalytic performance in terms of higher catalytic activity, selectivity, and durability for the oxygen reduction reaction.
Subduction initiation (SI) at passive continental margin plays a key role in the Wilson cycle of plate tectonics; however, the long‐lived, stable Atlantic‐type margin challenges this hypothesis. The ...spontaneous SI at passive margin is difficult, which could be instead induced by far‐field tectonic forces. Previous analog and numerical models are generally conducted with constant convergent velocity, which may lead to extremely large boundary force in order for SI. In this study, we focus on numerical models with constant convergent force/stress to investigate the conditions for SI at typical passive margin without any type of prescribed weak zones. The result indicates that the SI at young passive margins with thin oceanic lithosphere is much easier than that at old margins. It reveals the dynamics of multiple newly formed subduction zones in the young oceanic plates of Southeast Asia and Southwest Pacific, but generally no SI for the old Atlantic‐type passive margin.
Plain Language Summary
Subduction, which is a plate moves under another one and sinks into the mantle, is a key process of the Earth. Subduction could cause disasters, shape magnificent natural wonders, and control the long‐term climate. However, our understanding for how and where subduction would begin between continents and oceans is still poor. This is because the beginning of subduction is just a snapshot of long‐lived geological process. Thus, the rock records are rather limited and difficult to observe. In this study, we conducted systematic numerical models to quantify the force required for the formation of a new subduction zone with variable ages of oceanic lithosphere. The result indicates that the force needed to begin subduction increases with the oceanic age, which explains that young oceanic plates in the Southeast Asia and Southwest Pacific are easier to begin subduction; however, the old Atlantic Oceanic plate is hard.
Key Points
Subduction initiation at passive continental margin is studied by numerical model with convergent force/stress boundary condition
Mode selection of subduction initiation and required magnitude of force are dependent on the age of passive marginal oceanic lithosphere
Young oceanic lithosphere is easier to initiate subduction with low boundary force, whereas the old Atlantic‐type margin is difficult
Identifying effective means to improve the electrochemical performance of oxygen‐evolution catalysts represents a significant challenge in several emerging renewable energy technologies. Herein, we ...consider metal–nitrogen–carbon sheets which are commonly used for catalyzing the oxygen‐reduction reaction (ORR), as the support to load NiO nanoparticles for the oxygen‐evolution reaction (OER). FeNC sheets, as the advanced supports, synergistically promote the NiO nanocatalysts to exhibit superior performance in alkaline media, which is confirmed by experimental observations and density functional theory (DFT) calculations. Our findings show the advantages in considering the support effect for designing highly active, durable, and cost‐effective OER electrocatalysts.
Sitting on the FeNC: Metal–nitrogen–carbon sheets are used as the supports for metal oxide catalysts for the oxygen‐evolution reaction (OER). Iron–nitrogen–carbon (FeNC) sheets loaded with NiO nanoparticles give superior performance in alkaline media. The improved performance originates from a synergistic effect between the FeNC sheets and NiO.
The development of an efficient catalytic electrode toward both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of great significance for overall water splitting associated ...with the conversion and storage of clean and renewable energy. In this study, carbon paper/carbon tubes/cobalt-sulfide is introduced as an integrated three-dimensional (3D) array electrode for cost-effective and energy-efficient HER and OER in alkaline medium. Impressively, this electrode displays superior performance compared to non-noble metal catalysts reported previously, benefiting from the unique 3D array architecture with increased exposure and accessibility of active sites, improved vectorial electron transport capability, and enhanced release of gaseous products. Such an integrated and versatile electrode makes the overall water splitting proceed in a more direct and smooth manner, reducing the production cost of practical technological devices.
In the regime of plate tectonics, the subduction of an oceanic plate generally terminates with the collision and accretion of continental terranes. Then, a new subduction zone may form in the ...neighboring oceanic plates, which is defined as the terrane collision‐induced subduction initiation (SI). Based on the analyses of the western Pacific subduction system in the Cenozoic, three types of collision‐induced SI have been observed: subduction polarity reversal, subduction transference and far‐field subduction. However, the dynamics and controlling factors of SI mode selection after terrane collision are not clear. In this study, a multi‐terrane collision model has been conducted with variable rheological strength of continental terranes and different convergence velocities. The model results indicate that the relative strength of the terranes controls the SI mode selection, with the new subduction zone tending to form beneath weaker terranes. In addition, the higher convergence velocity can facilitate the collision‐induced SI. An analytical study of force balance has been further conducted, which provides a mechanical explanation for the numerical prediction of a weak overriding terrane as a favorable SI site. The numerical models and force balance analyses are further compared with the natural cases in the western Pacific subduction system. This indicates that subduction polarity reversal is the most favorable mode after terrane collision in the western Pacific, possibly due to the weakness of overriding plate during the preceding subduction‐induced fluid/melt activity. This comprehensive study provides systematic constraints for the dynamics of collision‐induced subduction jump, especially for the western Pacific subduction zones in the Cenozoic.
Plain Language Summary
The Earth's rocky surface is composed of both oceanic and continental crusts. The oceanic plate is denser and can sink into the Earth's interior as a subducting slab. A specific subduction process terminates when the whole oceanic plate is consumed and the neighboring continental blocks collide together. Then, the continued convergence may lead to the formation of a new subduction zone in the neighboring oceanic plate; however, the localization of new subduction zone varies. In the western Pacific subduction system in the Cenozoic, a new subduction zone may form in three different positions of the overriding and subducting plates. The mode selection of the new subduction zone formation plays an important role in Earth's plate tectonic evolution; however, its mechanism is not clear. In this study, systematic numerical models and force balance analyses have been conducted, which indicate that the relative strength of the continental blocks controls the position of new subduction zone formation, which favors the formation beneath weaker blocks. This prediction is further confirmed by the natural cases in the western Pacific system. This comprehensive study improves our understanding of the formation of new subduction zones as well as the more general subduction dynamics and plate tectonics.
Key Points
Terrane collision may lead to three different modes of subduction jump: polarity reversal, transference, and far‐field subduction
The collision‐induced subduction initiation prefers to occur beneath the rheologically weak overriding terrane
Subduction polarity reversal is the dominant mode in the western Pacific due to the widely distributed rheologically weak island arc
Nitrogen‐doped carbon (NC) materials have been proposed as next‐generation oxygen reduction reaction (ORR) catalysts to significantly improve scalability and reduce costs, but these alternatives ...usually exhibit low activity and/or gradual deactivation during use. Here, we develop new 2D sandwich‐like zeolitic imidazolate framework (ZIF) derived graphene‐based nitrogen‐doped porous carbon sheets (GNPCSs) obtained by in situ growing ZIF on graphene oxide (GO). Compared to commercial Pt/C catalyst, the GNPCSs show comparable onset potential, higher current density, and especially an excellent tolerance to methanol and superior durability in the ORR. Those properties might be attributed to a synergistic effect between NC and graphene with regard to structure and composition. Furthermore, higher open‐circuit voltage and power density are obtained in direct methanol fuel cells.
Nitrogen‐doped: A new oxygen reduction reaction electrocatalyst was obtained from ZIF‐derived porous carbon and graphene. The catalyst exhibits high activity, superior tolerance to methanol, and good stability in comparison to commercial Pt/C catalyst.
Oxygen evolution: A 3D nickel foam/porous carbon/anodized nickel electrode was designed for the oxygen evolution reaction (see picture). The conductive porous carbon membrane, which is derived from a ...zeolite imidazolate framework, plays a key role as an interlayer to both protect the inner instable Ni foam and support the outermost oxygen‐evolving Ni catalyst layer.
To turn waste into treasure, a facile and cost‐effective strategy is developed to revive electroless nickel plating wastewater and cotton‐textile waste toward a novel electrode substrate. Based on ...the substrate, a binder‐free PB@GO@NTC electrode is obtained, which exhibits superior electrochemical performance. Moreover, for the first time, a novel tube‐type flexible and wearable sodium‐ion battery is successfully fabricated.
Abstract India‐Asia collision is generally believed to have collided since 55 ± 5 Ma, with a total amount of convergence of 2900–4400 km. Besides the overriding Tibetan lithospheric shortening, a ...large amount of convergence has to be accommodated by the subducting plate of Greater India. Three typical India‐Asia collision models have been proposed, including the Greater Indian Continent (GIC) model, Intra‐Oceanic Arc model and Greater Indian Oceanic Basin model. In this study, a large‐scale 2D numerical model, driven by the reconstruction‐based India‐Asia convergence rate, have been conducted to evaluate these three major models. The model results indicate that the one‐stage GIC model favours later initial collision at ≤50 Ma. For the two‐stage collision, the large amount of convergence can be easily accommodated by modifying the length of oceanic subduction after the first stage of continental collision. This study provides systematic numerical constraints for the favourable conditions of each model.
A number of geophysical observations reveal that the underthrusting Indian continental plate beneath the southern Tibetan Plateau is laterally torn and segmented, with contrasting subduction angles ...along strike. However, the mechanism of such kind of slab tearing remains unclear. Here, a series of 3‐D high‐resolution numerical models are conducted, which suggest that the lateral variation (either gradually or abruptly changing) of boundary convergence rate plays a critical role in the tearing of underthrusting continental slab. The abruptly changing convergence with a large lateral contrast could lead to slab tearing all by itself, whereas the gradually changing convergence should be combined with pre‐existing weakness in the underthrusting block. The structures and properties of overriding block play secondary roles. Finally, we propose that Indian slab tearing could be attributed to the time‐dependent and lateral variation of convergence rate during the Indian‐Asian collision and the pre‐existing Indian lithospheric weakness.
Plain Language Summary
Horizontal slab tearing associated with the final slab break‐off occurs in many places of the global subduction‐collision system, the mechanism of which is easier for understanding and is mainly driven by the negative buoyancy of the subducted slab. However, for the underthrusting Indian continental plate beneath the southern Tibetan Plateau, the slab tearing and fragmentation occurs along several vertical planes perpendicular to the collision zone, which is identified by a number of geophysical explorations. It is rather difficult for a coherent subducting slab to tear along these sub‐vertical planes due to the lack of major forces in the along‐strike direction. Thus, the mechanism of Indian slab tearing is widely debated and remains unclear. In this study, many speculations have been tested by conducting a series of 3‐D high‐resolution numerical models. The model results indicate that the Indian slab tearing may be resulted from the time‐dependent and lateral variation of convergence rate between the Indian‐Asian collision and the resulting rotation of Indian continent, as well as the pre‐existing weakness within the Indian plate. Alternatively, the structures and properties of overriding Tibetan plate only play secondary roles.
Key Points
Systematic 3‐D numerical models are conducted to study the mechanism of Indian slab tearing along vertical planes beneath Tibetan Plateau
Lateral variation of boundary convergence rate (either abruptly or gradually changing) is generally required for such slab tearing
Indian slab tearing may be attributed to the gradually changing collision rate along strike and the pre‐existing lithospheric weakness
