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Pure hexagonal β -NaYF4 micron crystals were synthesized by the hydrothermal method with the up-conversion luminescence properties studied by doping Yb 3 + /Ho 3 + . The up-conversion fluorescence spectra and fluorescence lifetime of β -NaYF4 micron crystals were determined by FLS-980 transient fluorescence spectrometer. By changing the doping concentration of Yb 3 + /Ho 3 + , the optimal doping concentration was confirmed to be 20%Yb 3 + /2%Ho 3 + . The fluorescence spectrum was obtained by changing pump power, the relationship between power and intensity was analyzed, and the β -NaYF4 micron crystal green and red emission up-conversion process was obtained into a two-photon process. The 5F 4 → 5 I8 and 5S 2 → 5 I8 of the sample were thermally coupled to obtain a large absolute sensitivity (Sa) of low temperature. The maximum absolute sensitivity within the range of 64–194 K is 0.0097 K − 1 at 144 K, while maximum absolute sensitivity at 333 K is 0.00335 K − 1 in the range of 293–493 K. The experimental results show that the sensing characteristics of β -NaYF4:Yb 3 + /Ho 3 + at low temperature are better than those at high temperature, and it has the potential to be used in the field of temperature sensing. [ABSTRACT FROM AUTHOR]

Developing metal-free carbon electrocatalysts with atomically precise structures of hetero-doping is crucial for inventing reliable alternatives to precious metal-based catalysts. Our study reveals that the optimal active site is the edge-exposed N-neighbored carbon site in a chained N- C -C-S structure. Carbon material with N- C -C-S functional doping is controllably synthesized through polymer dehalogenation and heteroatom doping with thiomorpholine at room temperature. The resulting N/S-co-doped carbon with N- C -C-S functionalization, named N-C 2 -S, exhibits excellent ORR performance compared to other types of N, S-co-doped carbon, and commercial Pt/C. Typically, the N-C 2 -S sample shows the earliest onset potential of 0.96 V and a high half-wave potential of 0.85 V for promoting ORR. Assembled into an Al-air battery, The N-C 2 -S delivers an exceptional open-circuit voltage of 1.95 V and a large specific power of 128.1 mW cm 2. The synthesis strategy developed in this work can potentially open up precise functionalization of synthetic carbons with heteroatoms. [Display omitted] • The C site near the N in N-C-C-S is identified as highly active for oxygen reduction. • Different types of N, S-co-doped carbon are obtained via dehalogenation of PVDC. • N-C-C-S doping is realized via dehalogenation coupling reaction with thiomorpholine. • The N-C 2 -S sample exhibits exceptionally good oxygen reduction reaction performance. • The N-C 2 -S-assembled Al-air battery delivers high cell voltages and large powers. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel Cu/NBC was fabricated by modifying N-doped biochar with Cu MOF-derived Cu. • Cu/NBC exhibited superior desulfurization capacity of 158.28 mg/g at low temperature. • The main desulfurization products of H 2 S were composed of sulfur and copper sulfide. • Desulfurization mechanism involved synergistic catalytic oxidation and adsorption. Hydrogen sulfide (H 2 S) is a highly toxic and corrosive gas that poses significant risks to human health and the environment. Therefore, the development of an adsorbent capable of efficiently purifying H 2 S at room temperature remains a challenging task. In this study, a novel composite adsorbent with a specific surface area of 434 m2·g−1 was fabricated by modifying porous N-doped biochar with Cu nanoparticles (Cu/NBC) derived from Cu-MOFs for low-temperature desulfurization of H 2 S. The effect of pyrolysis temperature and the doping ratio of Cu-MOFs to biochar on the desulfurization performance of H 2 S for the as-prepared Cu/NBC was comprehensively investigated. Experimental results indicated that the desulfurization capability of the optimized Cu/NBC-600-1 adsorbent (synthesized at a pyrolysis temperature of 600 °C and a doping ratio of 1:1) was significantly affected by the desulfurization conditions, and the optimal conditions were determined to be at 25 °C, with 20 % oxygen content and 70 % relative humidity. Under the optimized conditions, the Cu/NBC-600-1 adsorbent exhibited a high H 2 S removal capacity of 158.28 mg·g−1, which was about 3.8 times higher than that of the pristine N-doped biochar. The desulfurization mechanism of the Cu/NBC composite was demonstrated to involve reactive adsorption and catalytic oxidation, resulting in the formation of elemental sulfur and copper sulfides as the main products. This study not only provides a promising approach to modify porous biochar with MOF derivatives, but also offers an effective strategy to remove low concentration H 2 S at room temperature. [ABSTRACT FROM AUTHOR]