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Stimuli-responsive hydrogels can respond to external stimuli with a change in the network structure and thus have potential application in drug release, intelligent sensing, and scaffold construction. Peptides possess robust supramolecular self-assembly ability, enabling spontaneous formation of nanostructures through supramolecular interactions and subsequently hydrogels. Therefore, peptide-based stimuli-responsive hydrogels have been widely explored as smart soft materials for biomedical applications in the last decade. Herein, we present a review article on design strategies and research progress of peptide hydrogels as stimuli-responsive materials in the field of biomedicine. The latest design and development of peptide hydrogels with responsive behaviors to stimuli are first presented. The following part provides a systematic overview of the functions and applications of stimuli-responsive peptide hydrogels in tissue engineering, drug delivery, wound healing, antimicrobial treatment, 3D cell culture, biosensors, etc. Finally, the remaining challenges and future prospects of stimuli-responsive peptide hydrogels are proposed. It is believed that this review will contribute to the rational design and development of stimuli-responsive peptide hydrogels toward biomedical applications. [ABSTRACT FROM AUTHOR]

Amorphous high-entropy alloys (HEAs) as electromagnetic-wave absorbing materials have been rarely reported. In this work, amorphous FeCoNiTixSi HEAs were synthesized by introducing a high content of large-atom Ti using the high-energy ball-milling technique. This amorphous structure could improve the saturated magnetization and coercivity of HEAs, but slightly degraded the mechanical and oxidation resistance properties. In terms of electromagnetic properties, FeCoNiTi0.01Si and FeCoNiTiSi exhibit excellent electromagnetic-wave absorption performances, with significant absorptions of −68.4 dB at 6.14 GHz and −63.4 dB at 9.12 GHz, corresponding to bandwidths of 5.15 GHz (1.69 mm) and 3.64 GHz (1.43 mm), respectively. Overall, the prepared FeCoNiTixSi HEAs exhibited superior comprehensive performances compared to other HEA absorption materials. This work provided a novel strategy for the development of new electromagnetic-wave absorption materials with low weight, high absorption efficiency, and resistance to harsh environments. [ABSTRACT FROM AUTHOR]

FeCoNiCuxMn (x = 0, 0.1, 0.3, 0.5, 0.7 and 0.9) and FeCoNiCu0.1MnB0.05 high entropy alloys (HEAs) were prepared via an improved swing ball-milling method. The BCC structure and FCC structure coexisted in the HEAs, and the proportion of FCC structure presented an increasing tendency with the increase of Cu content. In terms of corrosion resistance, Cu segregation generated galvanic corrosion, and weakened the corrosion resistance. A small amount of Cu had little effect on the oxidation resistance at high temperatures, but when the Cu content was high (FeCoNiCu0.9Mn), the oxidation resistance of the alloys at 1000 °C was enhanced due to the formation of CuO protective layers. The introduction of boron reduced the oxidation rate and enhanced the initial oxidation temperature but weakened the corrosion resistance and impedance matching. The optimal reflection loss (RLmin) of FeCoNiCu0.1Mn reached −71.0 dB as thin as 2.93 mm, and the widest bandwidth was 6.79 GHz (7.75–14.54 GHz). This work has important significance for the exploration of practical EMA materials that are resistant to harsh environments. [ABSTRACT FROM AUTHOR]

Two porphyrin sensitizers, SGT-023 and SGT-025, were synthesized through acceptor structural engineering. SGT-023 was designed by replacing the commonly used benzothiadiazole (BTD) unit in the well-known platform of D-porphyrin-triple bond-BTD-acceptor sensitizers (e.g., SM315 and SGT-021) with a pyridothiadiazole unit as a stronger electron-withdrawing group. As for SGT-025, an additional ethynylene bridge was inserted into the acceptor part of the well-known skeleton of D-porphyrin-triple bond-BTD-acceptor sensitizers. The impact of the auxiliary acceptors on the optical, electrochemical, and photovoltaic properties was investigated and compared with a benchmark dye, SGT-021, developed by our group. Consequently, both porphyrin sensitizers could red-shift the absorption range and downshift the lowest unoccupied molecular orbital (LUMO) energy level, which was supposed to achieve higher light harvest efficiency (LHE). Under standard global AM 1.5G solar light conditions, SGT-025 attained a relatively high maximum power conversion efficiency (PCE) of 11.0%, which was slightly lower than that of the reference dye SGT-021 (12.6%), and a moderate PCE of 5.6% was obtained by SGT-023. The main reason is the lower charge collection efficiency, which can be attributed to the tilted dye adsorption mode on TiO2. This may allow for faster charge recombination which eventually leads to lower Jsc, Voc and PCE. [ABSTRACT FROM AUTHOR]

Increasing energy consumption worldwide and environmental concerns about global warming have attracted great interest in the development of renewable and eco-friendly energy technologies. Dye-sensitized solar cells (DSSCs) have attracted considerable attention over the last 25 years since they offer possible low-cost conversion of photovoltaic energy. The sensitizer is the most important component of a DSSC, as it is largely responsible for light harvesting and charge separation, as well as the dye regeneration process. As a result, there have been tremendous research efforts in developing sensitizers. However, many challenges remain, and a deeper understanding of the design rules of DSSC sensitizers is required to obtain efficient and long-term stable DSSCs. The purpose of this review is to discuss recent progress and the rational design criteria used in the structural design of organic dyes and porphyrin photosensitizers for use in DSSCs. The effects of molecular structural engineering on the photophysical and electrochemical properties, photovoltaic parameters, and efficiency of DSSCs are presented. [ABSTRACT FROM AUTHOR]

Strontium titanate (SrTiO3) nanocrystals have been synthesized by a hydrothermal reaction route using anatase TiO2 nanosheets with dominant {001} facets and commercial anatase TiO2 nanoparticles as precursors. Time-resolved quenching experiments showed that the speed of hydrothermal formation of SrTiO3 was relatively fast (in minutes). The initial particle morphology and exposed crystal facets of anatase TiO2 precursor cannot be retained in the final SrTiO3 products. SrTiO3 nuclei are formed by the reaction between Ti(OH)x4−x and Sr ions at the TiO2 solid/liquid interface. As surface adsorbed F− is necessary to stabilize the {001} facets of anatase TiO2, the hydrothermal crystallization of SrTiO3 from TiO2 with {001} facets not only exhibits a slower reaction rate but also a higher activation energy. Moreover, the photoelectrochemical and photocatalytic activity studies indicated that the SrTiO3 products obtained from TiO2 with {001} facets showed enhanced photocurrent density and photocatalytic hydrogen production activity. The present study sheds some light on the understanding of the crystal facets of the precursor on the hydrothermal formation process as well as the photocatalytic activities of the corresponding products. [ABSTRACT FROM AUTHOR]

Amorphous high-entropy alloys (HEAs) as electromagnetic-wave absorbing materials have been rarely reported. In this work, amorphous FeCoNiTi x Si HEAs were synthesized by introducing a high content of large-atom Ti using the high-energy ball-milling technique. This amorphous structure could improve the saturated magnetization and coercivity of HEAs, but slightly degraded the mechanical and oxidation resistance properties. In terms of electromagnetic properties, FeCoNiTi 0.01 Si and FeCoNiTiSi exhibit excellent electromagnetic-wave absorption performances, with significant absorptions of -68.4 dB at 6.14 GHz and -63.4 dB at 9.12 GHz, corresponding to bandwidths of 5.15 GHz (1.69 mm) and 3.64 GHz (1.43 mm), respectively. Overall, the prepared FeCoNiTi x Si HEAs exhibited superior comprehensive performances compared to other HEA absorption materials. This work provided a novel strategy for the development of new electromagnetic-wave absorption materials with low weight, high absorption efficiency, and resistance to harsh environments.