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Urea electrolysis is an appealing energy conversion technology to produce hydrogen (H2) and alleviate the problem of urea-rich wastewater treatment concurrently. In particular, electrocatalytic performance can be dramatically enhanced by rationally modulating the surface charge distribution with a well-tuned heterostructure. Herein, a heterostructure is constructed by NiMoO4 nanosheets grown on an interior hollow NiS@Ni3S2 nanorods framework (NiS@Ni3S2/NiMoO4). Density functional theory (DFT) calculations demonstrate that the formed heterojunction structure leads to a tailored surface charge state of NiMoO4, with oxygen as the nucleophilic region and molybdenum as the electrophilic region, which facilitates the decomposition of urea molecules and thus significantly improves hydrogen evolution. As expected, the assembled NiS@Ni3S2/NiMoO4 system substantially expedites urea electrolysis activity with a cell voltage of 1.40 V at 10 mA cm−2, which is 200 mV less than the voltage of an overall water splitting system. [ABSTRACT FROM AUTHOR]

The production and storage of hydrogen are the two most critical challenges for hydrogen energy development. In addition, converting H2 from the as-obtained gas state to a stable storage state consumes excess energy and increases the practical cost of hydrogen fuel. Accordingly, we now present a simple hybrid material system (Co/TiO2) that efficiently synchronizes hydrogen photogeneration in water with its room-temperature storage. In the composite, through a series of carefully controlled experiments, ultrathin Co shells composed of 1, 2, 4, and 9 atom layers have been fabricated on TiO2 photocatalysts. Before saturation of hydrogen on metal Co, the hydrogen storage efficiency is close to 100%, meaning that nearly all hydrogen generated by photocatalytic water splitting is conserved. This work provides a new approach to combined structure-function design technology in the hydrogen energy field. [ABSTRACT FROM AUTHOR]

Exploring cost-efficient/durability bifunctional electrocatalysts are of upmost importance for the practical application of metal-air batteries. However, preparing bifunctional electrocatalysts with the above three advantages remains conceptually challenging. This work reports the preparation of N-doped carbon confined NiCo alloy hollow spheres (NiCo@N-C HS) as bifunctional oxygen electrocatalyst for Zn-air battery with a higher energy density (788.7 mWh g Zn -1 ) and outstanding cycling stability (over 200 h), which are more durable than the commercialized Pt/C+RuO 2 -based device. Electrochemical results and theoretical calculation demonstrate that the synergy in the NiCo@N-C accelerates the electronic transmission for improving activation of O 2 * and OH* intermediates and optimizing reacted free energy pathways, while the hollow structures exposure more active sites for improving the reaction kinetics and enhancing the activity of ORR/OER reaction. This work provides crucial understanding for constructing low-cost transition metal-based catalyst to overcome the efficiency and durability barriers of metal-air batteries for widespread applications., (© 2023 Wiley-VCH GmbH.)

Reasonable development of high-efficiency and robust electrocatalysts for efficient electrocatalytic water splitting at high current density is hopeful for renewable energy, but the real challenge is substituting the precious metal catalysts. Herein, ultrathin Fe-modified Ni 2 P/Ni 5 P 4 nanosheet arrays hybridized with N-doped carbon grown on Ni foam (Fe-Ni 2 P/Ni 5 P 4 @N-C) were synthesized via a solvothermal-pyrolysis strategy. Theoretical calculations and in situ Raman characterizations confirm that the Fe sites can facilitate the surface reconstruction of highly active NiOOH species and significantly lower the energy barrier for the formation of the *OOH intermediate owing to the electron coupling effect between Fe and the Ni 2 P/Ni 5 P 4 heterostructure. On account of the structural advantages and compositional synergy, the optimized Fe-Ni 2 P/Ni 5 P 4 @N-C exhibits superior hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activities with an overpotential of 105 and 280 mV to reach 10 and 50 mA cm -2 , respectively, and can work stably for 60 h at 100 mA cm -2 . Impressively, the electrolyzer with Fe-Ni 2 P/Ni 5 P 4 @N-C only needs 1.56 V to achieve 10 mA cm -2 current density for water splitting. This protocol not only provides inspiration for designing transitional metal electrocatalysts for water splitting but also puts forward a pathway for practical application.

Rationally designing interface structure to modulate the electronic structure of a photocatalyst is an efficient strategy to facilitate the separation and migration of photogenerated charge carriers and improve photocatalytic activity. In this work, a AgCl/Pd heterostructure encapsulated by N-doped carbon nanotubes (AgCl/Pd@N-C) with a fan-like morphology assembled hollow tubes was synthesized by pyrolysis of a AgCl/Pd@Bim precursor. The unique interface structure not only increases the number of photogenerated charge carriers, but also provides an effective channel for the separation of electrons and holes, which have been proved by density functional theory (DFT) calculations. As expected, the obtained AgCl/Pd-3@N-C exhibited greatly enhanced conversion efficiency and recyclability toward the photocatalytic oxidative coupling of amine under blue-light irradiation., (© 2022 Wiley-VCH GmbH.)

The construction of semiconductor composites is known as a powerful method used to realize the spatial separation of electrons and the holes in them, which can result in more electrons or holes and increase the dispersion of oxygen ions ([Formula: see text] and O - ) (one of the most critical factors for their gas-sensing properties) on the surface of the semiconductor gas sensor. In this work, using 1D ZnO/ZnSnO 3 nanoarrays as an example, which are prepared through a hetero-epitaxial growing process to construct a chemically bonded interface, the above strategy to attain a better semiconductor gas-sensing property has been realized. Compared with single ZnSnO 3 nanotubes and no-matching ZnO/ZnSnO 3 nanoarrays gas sensors, it has been proven by x-ray photoelectron spectroscopy and photoluminescence spectrum examination that the as-obtained ZnO/ZnSnO 3 sensor showed a greatly increased quantity of active surface electrons with exceptional responses to trace target gases and much lower optimum working temperatures (less than about 170 °C). For example, the as-obtained ZnO/ZnSnO 3 sensor exhibited an obvious response and short response/recovery time (less than 10 s) towards trace H 2 S gas (a detection limit down to 700 ppb). The high responses and dynamic repeatability observed in these sensors reveal that the strategy based on the as-presented electron and hole separation is reliable for improving the gas-sensing properties of semiconductors.

Lithium-selenium batteries, employing selenium as a cathode material, exhibit some notable advantages, such as high discharge rates and good cycling performance, due to their high electrical conductivity, high output voltages, and high volumetric capacity density. However, an important problem, termed the "shuttle effect", can lead to capacity decay in Li-Se cells (and in Li-S cells), which arises from aggregation and the loss of Se or S from the cathode into the electrolyte. In this work, in order to solve this problem, a new self-repairing system has been devised, in which some Se atoms are chemically bonded to the carbon atoms of graphene and act as reclaiming points for dissociated Se atoms through the establishment of -Se-Se-Se- chains. Se-decorated graphene (Se-GE) was first constructed through a facile high-energy ball-milling process. Its formation was confirmed by XRD, SEM, HRTEM, XPS, and Raman analyses. As we anticipated, in examining cell properties, the as-prepared Se-GE composite underwent an initial capacity decay in the first 20 cycles (from 1050 mAh g -1 to 750 mAh g -1 , ca. 29 % loss), but the capacity then reverted to 970 mAh g -1 (ca. 92 % of the initial value). Other measurements were also consistent with the recapture of dissociated Se atoms., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)