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The preparation of ultra-small structurally ordered Pt-based intermetallic nanocrystals (< 3 nm) is still challenging due to the sintering during high temperature ordering. We report a strategy to construct size and distribution controllable Pt-based intermetallic nanocrystals based on ultra-thin metal oxide coating on Pt nanoparticles via atomic layer deposition. The area-selective and thickness controllable metal oxide coatings can not only provide metal atoms for alloying, but also prevent the sintering of Pt nanoparticles during subsequently fast ordering reduction. The prepared uniform PtZn intermetallic nanocrystals with the size of 2.50 ± 0.65 nm achieve outstanding single-cell performance with the mass activity of 0.48 A mg Pt −1 at 0.9 V and 10.42 % loss of mass activity after 30,000 voltage cycles, which is superior to commercial Pt/C. The enhanced activity and durability is attributed to the decreased binding energy of Pt-oxygen intermediates for weakly polarized surface Pt atoms and suppressed electrochemical Ostwald ripening. [Display omitted] • Uniform sub-3 nm PtZn intermetallic is synthesized by selectively coating ultra-thin ZnO on Pt nanoparticles via atomic layer deposition. • Ultra-thin ZnO coating can provide Zn atoms for alloying and prevent the sintering of nanoparticles during ordering reduction. • The enhanced activity is attributed to the decreased binding energy of Pt-oxygen intermediates for weakly polarized surface Pt atoms. • Sub-3 nm PtZn intermetallic nanocrystals with uniform size distribution suppress electrochemical Ostwald ripening in acid conditions. [ABSTRACT FROM AUTHOR]

A two-step heating strategy was proposed to fabricate transparent MgAlON ceramics by solid-state reaction of MgAl 2 O 4 and AlON powders via pressureless sintering. By dwelling 60 min at 1700 ℃ followed by 150 min at 1880 ℃, highly infrared transparent MgAlON ceramics with transmittance up to 80.4 % were successfully fast prepared. The phase transformation and microstructure evolution during heating from 1400 ℃ to 1800 ℃ and dwelling at 1700 ℃ for 0–90 min was thoroughly studied to reveal the solid-state reaction and densification mechanism of MgAlON by two-step heating. Surprisingly, it was found that the grown grains could break during dwelling at 1700 ℃. This secondary massive fragmentation of grown grains resulted in the minimized grain size and improved moveability of grains, which in turn prompted fast and high densification with pore free in the following sintering step. The grain breakage at 1700 ℃ could be attributed to the decomposition of AlON and formation of MgAlON. [ABSTRACT FROM AUTHOR]

Based on the reaction sequence during synthesis of MgAlON powder by solid-state reaction, a two-step heating strategy is proposed to low-temperature fabricate fine MgAlON powder of high sinterability by using MgAl 2 O 4 as Mg source, respectively together with AlON and Al 2 O 3 +AlN. By introduction of an additional dwelling at 1550 °C to the first heating step, more α-Al 2 O 3 dissolve into the solid solution at this temperature. By this way, overlarge particles of Al 2 O 3 by agglomeration could be avoided in the next heating step to enable fast full reaction at a lower temperature. By dwelling 30 min at 1550 °C followed by 60 min at 1700 °C, single phase MgAlON powders were successfully prepared by solid-state reaction of all the two batches. The fine MgAlON powder synthesized by MAS+Al 2 O 3 +AlN batch exhibited high sinterability as the MgAlON ceramics pressureless sintered by this powder at 1880 °C without dwelling showed a transmittance up to 68.3%. The phase assemblage and morphology evolution of the mixture during solid-state reaction were monitored, which verified the effectiveness of the proposed two-step heating strategy. The low synthesis temperature of the two-step heating scheme benefits to prepare pure MgAlON powder with small particle size. [ABSTRACT FROM AUTHOR]

The shipbuilding industry is a vital sector involved in manufacturing ships and marine structures. It serves critical roles in shipping, maritime development, and national defense, which contributes significantly to employment, international trade, and national security. Nevertheless, the shipbuilding industry is under enormous pressure to curtail carbon emissions. The International Maritime Organization (IMO) requires a 40% reduction in greenhouse gas emissions (GHG) from both existing and new ships by 2030 compared to the 2008 baseline. This stems from the industry's high-carbon emission nature, making it imperative to adopt sustainable solutions that minimize its environmental impact. Given the capital- and energy-intensive nature of the shipbuilding industry, the implementation of suitable technologies can also improve the overall operational efficiency while meeting shipowners' sustainability standards and enhancing competitiveness. We selected a typical shipbuilding company in South China and categorized the 11 key low-carbon technologies into four categories based on their principles and application scenarios, i.e., equipment improvement, process upgrading, intelligent upgrading, and fuel alternative. The Long-range Energy Alternatives Planning system (LEAP) model was employed in this study to simulate the energy consumption structure of this shipbuilding enterprise and explore pathways to reach carbon emissions peak under six low-carbon technology scenarios. In addition, the impact of dynamically changing grid emission factors on long-term carbon emission reduction is taken into consideration. The results show that a sustained reduction in grid emission factors will have a positive impact on carbon emission reduction. The shipyard's planned requirements to achieve carbon peak before 2030 and reduce its carbon intensity by 18% from 2020 are only achievable under the application of all low-carbon technologies. The shipyard will achieve carbon peak in 2026, with a maximum emission reduction potential of 13.2 thousand tons. The primary contributors are equipment improvement and process upgrading technologies, with reductions of 6.73 and 3.11 thousand tons, respectively. Therefore, from a technical point of view, these can be prioritized for development, although some of the equipment has a high upfront investment. Notably, the technology diffusion is rapid, with most technologies projected to reach penetration saturation by 2025, leading to a payback period of 3–4 years thereafter. • Considered the dynamic changes of grid emission factors. • Analyzed eleven low-carbon technologies in four categories and their combinations. • Provided technical solutions for the shipyard to meet emission reduction targets. • Analyzed the future development pathways from a technical perspective. [ABSTRACT FROM AUTHOR]

The intrinsic carbon defects including pentagons, vacancies and sp3-hybridized carbon have recently been proposed as efficient reactive sites for oxygen reduction reaction (ORR). Nevertheless, it is still a great challenge to controllably introduce the intrinsic defects into carbon materials. Herein, a universal defect-engineering method via vaporized salt is reported to modify the N-doped carbon surface with abundant sp3-hybridized carbon defects. At an elevated temperature, the vaporized sodium chloride is found to selectively modulate the surface structure of carbon material. The obtained carbon-based electrocatalyst delivers an outstanding electrocatalytic ORR property with a half-wave potential (E 1/2) of 0.85 V vs. RHE and an excellent performance in zinc air battery (ZAB) test. The analysis of components and structures of surface elements via XANES and XPS reveals that the increasing sp3-hybridized carbon defects, induced by the vaporized-salt modification, are responsible for the enhancement of ORR performance. The theoretical calculations further suggest the sp3 component hybridizes with original sp2 carbon, forming efficient sp2/sp3 hybridized carbon sites towards ORR. Additionally, other halide salts are proved to have the similar effect on promoting ORR activity and this method can expand to other carbon-based materials, suggesting its universality and significance in synthesis of defect-rich carbon-based materials. [Display omitted] • A universal defect-engineering method via vaporized salt halide was developed. • The vaporized-salt-treated catalysts exhibited a superior ORR activity. • XANES, XPS, Raman and DFT calculations were applied to reveal the active sites. • The raised ORR activity was induced by the increasing sp3 carbon defects. [ABSTRACT FROM AUTHOR]

[Display omitted] • The harmless treatment and resource utilization of As-enriched plant were realized. • The effectiveness of As in the original biochar was reduced. • Biochar prepared by co-precipitation loading iron can efficiently remove As(III). • The oxidation of As(III) existed during the As adsorption by Fe-BC300 and Fe-BC500. There were limited researches on the scientific disposal of As-enriched plants, and how to reduce the available As content in the processed products and improve the utilization value were the key. In this study, the effect and mechanism of biochar produced by the As-enriched Pteris vittate before and after modification on the removal of As(III) in water were studied. The results indicated that the available As contents of Fe-BC300 and Fe-BC500 were reduced by 78.7 % and 91.9 % compared to original biochars, respectively. Modified biochars not only had a large adsorption capacity for As(III) (50.3 and 39.7 mg/g), but also can efficiently oxidize As(III) to As(V). The removal rate of As(III) by modified biochar was still higher than 50% after 3 cycles. The increase of the point of zero charge and the introduction of Fe were the main reasons for its efficient adsorption and oxidation of As(III). [ABSTRACT FROM AUTHOR]

To effectively solve the electrochemical degradation problem of commercial Pt/C catalyst in fuel cell, nitrogen doped titania oxynitride (N-TiO 2) decorated Pt low-coordinated sites on a commercial Pt/C catalyst is achieved by coupling single-cycle selective atomic layer deposition of TiO 2 and following nitriding process that exhibits outstanding durability enhancement without changing the size distribution and wasting the electrochemical active area of Pt. [Display omitted] • TiO 2 was selectively decorated on Pt nanoparticles by atomic layer deposition. • The nitridation of TiO 2 stabilized the defect sites on Pt nanoparticles. • N-doped TiO 2 kept the exposure of Pt nanoparticles active sites. • N-doped TiO 2 decorated Pt/C showed durability promotion in fuel cell. The electrochemical dissolution of platinum (Pt) based nanoparticles and the consequent Pt active sites losses and particle aggregation have become a critical stability issue for the commercial proton exchange membrane fuel cell. Herein, nitrogen doped titania (N-TiO 2) stabilized Pt low-coordinated sites on a commercial Pt/C catalyst is achieved by simply coupling selective atomic layer deposition of TiO 2 and following nitrogen doping process. Selectively deposited N-TiO 2 on Pt nanoparticles keeps the exposure of Pt sites on (111) facets and increases the reduction states of Pt, which results in 1.7 times improvement of mass activity than commercial Pt/C. Besides, N-TiO 2 stabilized commercial Pt/C catalyst exhibits outstanding durability enhancement, showing only a 14.0% loss of mass activity after 30,000 potential cycles of rotating disk electrode tests and 91.7% retention after durability tests in humid fuel cell condition. The shielding role of N-TiO 2 could effectively inhibit the degradation of low-coordinated sites on Pt nanoparticles and maintain Pt size distribution, which is a promising strategy to prolong the lifetime of commercial Pt/C catalysts. [ABSTRACT FROM AUTHOR]

• A molten-salt-assisted thermal emitting method was developed to prepare Fe SACs. • The molten salt boosted the evaporation and transfer of Fe species from bulk Fe 2 O 3. • The gasified Fe species formed single-atom "Fe-N 4 -O 2 " sites on N-doped carbon. • The Fe-Z8NC&NaCl SACs exhibited a remarkable ORR activity in alkane media. • The method was valid for preparing other metal SACs (metal = Co, Mn, Cu and Ni). Efficient, durable and low-cost electrocatalysts that accelerate sluggish oxygen reduction reaction kinetics are urgently needed for the energy conversion techniques, such as metal-air batteries and fuel cells. In this work, we develop a molten-salt-assisted thermal emitting approach to transform the cheap and easily obtainable bulk ferric (III) oxide powder into a highly efficient Fe single atom catalyst for cathodic oxygen reduction reaction. Benefiting from the strong polarity force of ionized cations and anions, the molten salt effectively facilitates breakage of chemical bonding in bulk Fe 2 O 3 and volatilization of Fe species far below the melting point of Fe 2 O 3 (1841 K), lowering the consumption of energy and time needed in the synthetic procedure. The vaporized Fe species are subsequently anchored onto the surface of nitrogen-doped porous carbon, evolving the single-atom "Fe-N 4 -O 2 " site catalyst. The obtained catalyst presents an excellent oxygen reduction reaction performance with half-wave potential of 0.896 V vs RHE in alkaline media, comparable to the most efficient non-precious metal catalysts and outperforming the benchmark system Pt/C. Furthermore, this method is demonstrated to be valid for synthesis of non-noble-metal single atom catalysts (metal = Co, Mn, Cu, Ni) by changing different metal oxides precursors. [ABSTRACT FROM AUTHOR]

In this study, a Nb layer was deposited on Ti-6.5Al–2Zr–1Mo–1V alloys by the double glow plasma alloying technique and the effect of pre-diffusion of Nb in the Nb–N films on microstructure and mechanical properties was analyzed. The structure of pre-diffusion samples is characteristic of a thick inter-diffusion layer and a nitride gradient layer. This novel structure is beneficial for relieving the residual stress at the preparation process and the stress field were redistributed during loading because the properties were changed gradually along with the depth. In addition, the pre-processing of diffusion is believed to effectively increase the nitrogen permeation rate and further alter the Ti diffusion path, subsequently achieving the changed structure and phase composition of the Nb–N co-diffusion layer. Ball-on-disc wear tests were carried out at different loads for pre-diffusion and co-diffusion samples. The pre-diffusion sample and counter-ball all showed slighter damage than that of the co-diffusion sample. Image 1 • The pre-processing of Nb diffusion was performed, and the effect of pre-diffusion Nb for Nb-N co-diffusion was discussed in detail. • The Rietveld refinement method was used to further analyze the phase information. • The ratio of elastic work to plastic work was used to evaluate the load capacity of modified layer. • The wear track morphologies of modified sample and ball were observed to investigate the wear behavior. [ABSTRACT FROM AUTHOR]