Superenhancement Photon Upconversion Nanoparticles for Photoactivated Nanocryometer.

Highly doped lanthanide luminescent nanoparticles exhibit unique optical properties, providing exciting opportunities for many ground-breaking applications, such as super-resolution microscopy, deep-tissue bioimaging, confidentiality, and anticounterfeiting. However, the concentration-quenching effect compromises their luminescence efficiency/brightness, hindering their wide range of applications. Herein, we developed a low-temperature suppression cross-relaxation strategy, which drastically enhanced upconversion luminescence (up to 2150-fold of green emission) in Er3+-rich nanosystems. The cryogenic field opens the energy transport channel of Er3+ multiphoton upconversion by further suppressing phonon-assisted cross-relaxation. Our results provide direct evidence for understanding the energy loss mechanism of photon upconversion, deepening a fundamental understanding of the upconversion process in highly doped nanosystems. Furthermore, it also suggests the potential applications of upconversion nanoparticles for extreme ambient-temperature detection and anticounterfeiting.

Metastable Supramolecular Assembly of Simple Monomers Enabled by Confinement: Towards Aqueous Phase Room Temperature Phosphorescence.

The application of supramolecular assembly (SA) with room temperature phosphorescence (RTP) in aqueous phase has the potential to revolutionize numerous fields. However, using simple molecules with crystalline RTP to construct SA with aqueous phase RTP is hardly possible from the standpoint of forces. The reason lies in that the transition from crystal to SA involves a structure transformation from highly stable to more dynamic state, leading to increased non-radiative deactivation pathways and silent RTP signal. Here, with the benefit of the confinement from the layered double hydroxide (LDH), various simple molecules (benzene derivatives) can successfully form metastable SA with aqueous phase RTP. The maximum of RTP lifetime and efficiency can reach 654.87 ms and 5.02%, respectively. Mechanistic studies reveal the LDH energy trap can strengthen the intermolecular interaction, providing the prerequisite for the existence of metastable SA and appearance of aqueous phase RTP. The universality of this strategy will usher exploration into other multifunctional monomer, facilitating the development of SAs with aqueous phase RTP.

Electrocatalytic Upcycling of Biomass and Plastic Wastes to Biodegradable Polymer Monomers and Hydrogen Fuel at High Current Densities.

Transformation of biomass and plastic wastes to value-added chemicals and fuels is considered an upcycling process that is beneficial to resource utilization. Electrocatalysis offers a sustainable approach; however, it remains a huge challenge to increase the current density and deliver market-demanded chemicals with high selectivity. Herein, we demonstrate an electrocatalytic strategy for upcycling glycerol (from biodiesel byproduct) to lactic acid and ethylene glycol (from polyethylene terephthalate waste) to glycolic acid, with both products being as valuable monomers for biodegradable polymer production. By using a nickel hydroxide-supported gold electrocatalyst (Au/Ni(OH)2), we achieve high selectivities of lactic acid and glycolic acid (77 and 91%, respectively) with high current densities at moderate potentials (317.7 mA/cm2 at 0.95 V vs RHE and 326.2 mA/cm2 at 1.15 V vs RHE, respectively). We reveal that glycerol and ethylene glycol can be enriched at the Au/Ni(OH)2 interface through their adjacent hydroxyl groups, substantially increasing local concentrations and thus high current densities. As a proof of concept, we employed a membrane-free flow electrolyzer for upcycling triglyceride and PET bottles, attaining 11.2 g of lactic acid coupled with 9.3 L of H2 and 13.7 g of glycolic acid coupled with 9.4 L of H2, respectively, revealing the potential of coproduction of valuable chemicals and H2 fuel from wastes in a sustainable fashion.

Manipulating the Injected Energy Flux via Host-Sensitized Nanostructure for Improving Multiphoton Upconversion Luminescence of Tm3.

Combating the concentration quenching effect by increasing the concentration of sensitized rare-earth ions in rational design upconversion nanostructure will make it easier to utilize injection energy flux and transfer it to emitters, resulting in improved upconversion luminescence (UCL). We proposed a host-sensitized nanostructure (active core@luminescent shell@inert shell) to improve multiphoton UCL of Tm3+ based on the LiLnF4 host. Yb3+ ions were isolated in the core as energy absorbents, and Tm3+ was doped in the interior LiYbF4 host shell. Compared with sandwich structured nanocrystals (Y@Y:Yb/Tm@Y), reverse structure (YbTm@Yb@Y), and fully doped structure (YbTm@YbTm@Y), the proposed structure achieved the highest efficiency of multiphoton UCL and favored a better FRET-based application performance as the Tm3+ located at an optimized spatial distribution. Furthermore, steady-state and dynamic analysis results demonstrate that by manipulating the spatial distribution of the active ions, excited energy can be tuned to enable multiphoton upconversion enhancement, overcoming the conventional limitations.

Selective Photoelectrocatalytic Glycerol Oxidation to Dihydroxyacetone via Enhanced Middle Hydroxyl Adsorption over a Bi2O3-Incorporated Catalyst.

Photoelectrocatalytic (PEC) glycerol oxidation offers a sustainable approach to produce dihydroxyacetone (DHA) as a valuable chemical, which can find use in cosmetic, pharmaceutical industries, etc. However, it still suffers from the low selectivity (≤60%) that substantially limits the application. Here, we report the PEC oxidation of glycerol to DHA with a selectivity of 75.4% over a heterogeneous photoanode of Bi2O3 nanoparticles on TiO2 nanorod arrays (Bi2O3/TiO2). The selectivity of DHA can be maintained at ∼65% under a relatively high conversion of glycerol (∼50%). The existing p-n junction between Bi2O3 and TiO2 promotes charge transfer and thus guarantees high photocurrent density. Experimental combined with theoretical studies reveal that Bi2O3 prefers to interact with the middle hydroxyl of glycerol that facilitates the selective oxidation of glycerol to DHA. Comprehensive reaction mechanism studies suggest that the reaction follows two parallel pathways, including electrophilic OH* (major) and lattice oxygen (minor) oxidations. Finally, we designed a self-powered PEC system, achieving a DHA productivity of 1.04 mg cm-2 h-1 with >70% selectivity and a H2 productivity of 0.32 mL cm-2 h-1. This work may shed light on the potential of PEC strategy for biomass valorization toward value-added products via PEC anode surface engineering.

Selectively Upgrading Lignin Derivatives to Carboxylates through Electrochemical Oxidative C(OH)-C Bond Cleavage by a Mn-Doped Cobalt Oxyhydroxide Catalyst.

Oxidative cleavage of C(OH)-C bonds to afford carboxylates is of significant importance for the petrochemical industry and biomass valorization. Here we report an efficient electrochemical strategy for the selective upgrading of lignin derivatives to carboxylates by a manganese-doped cobalt oxyhydroxide (MnCoOOH) catalyst. A wide range of lignin-derived substrates with C(OH)-C or C(O)-C units undergo efficient cleavage to corresponding carboxylates in excellent yields (80-99 %) and operational stability (200 h). Detailed investigations reveal a tandem oxidation mechanism that base from the electrolyte converts secondary alcohols and their derived ketones to reactive nucleophiles, which are oxidized by electrophilic oxygen species on MnCoOOH from water. As proof of concept, this approach was applied to upgrade lignin derivatives with C(OH)-C or C(O)-C motifs, achieving convergent transformation of lignin-derived mixtures to benzoate and KA oil to adipate with 91.5 % and 64.2 % yields, respectively.

Precisely Tailoring Upconversion Dynamics via Energy Migration in Core-Shell Nanostructures.

Upconversion emission dynamics have long been believed to be determined by the activator and its interaction with neighboring sensitizers. Herein this assumption is, however, shown to be invalid for nanostructures. We demonstrate that excitation energy migration greatly affects upconversion emission dynamics. "Dopant ions' spatial separation" nanostructures are designed as model systems and the intimate link between the random nature of energy migration and upconversion emission time behavior is unraveled by theoretical modelling and confirmed spectroscopically. Based on this new fundamental insight, we have successfully realized fine control of upconversion emission time behavior (either rise or decay process) by tuning the energy migration paths in various specifically designed nanostructures. This result is significant for applications of this type of materials in super resolution spectroscopy, high-density data storage, anti-counterfeiting, and biological imaging.

ABT737 enhances cholangiocarcinoma sensitivity to cisplatin through regulation of mitochondrial dynamics.

Cholangiocarcinoma responses weakly to cisplatin. Mitochondrial dynamics participate in the response to various stresses, and mainly involve mitophagy and mitochondrial fusion and fission. Bcl-2 family proteins play critical roles in orchestrating mitochondrial dynamics, and are involved in the resistance to cisplatin. Here we reported that ABT737, combined with cisplatin, can promote cholangiocarcinoma cells to undergo apoptosis. We found that the combined treatment decreased the Mcl-1 pro-survival form and increased Bak. Cells undergoing cisplatin treatment showed hyperfused mitochondria, whereas fragmentation was dominant in the mitochondria of cells exposed to the combined treatment, with higher Fis1 levels, decreased Mfn2 and OPA1 levels, increased ratio of Drp1 60kD to 80kD form, and more Drp1 located on mitochondria. More p62 aggregates were observed in cells with fragmented mitochondria, and they gradually translocated to mitochondria. Mitophagy was induced by the combined treatment. Knockdown p62 decreased the Drp1 ratio, increased Tom20, and increased cell viability. Our data indicated that mitochondrial dynamics play an important role in the response of cholangiocarcinoma to cisplatin. ABT737 might enhance cholangiocarcinoma sensitivity to cisplatin through regulation of mitochondrial dynamics and the balance within Bcl-2 family proteins. Furthermore, p62 seems to be critical in the regulation of mitochondrial dynamics.

Interplay between Defects and Short-Range Disorder Manipulating the Oxygen Evolution Reaction on a Layered Double Hydroxide Electrocatalyst.

Improving the efficiency of the oxygen evolution reaction (OER) is crucial for advancing sustainable and environmentally friendly hydrogen energy. Layered double hydroxides (LDHs) have emerged as promising electrocatalysts for the OER. However, a thorough understanding of the impact of structural disorder and defects on the catalytic activity of LDHs remains limited. In this work, a series of NiAl-LDH models are systematically constructed, and their OER performance is rigorously screened through theoretical density functional theory. The acquired results unequivocally reveal that the energy increase induced by structural disorder is effectively counteracted at the defect surface, indicating the coexistence of defects and disorder. Notably, it is ascertained that the simultaneous presence of defects and disorder synergistically augments the catalytic activity of LDHs in the context of the OER. These theoretical findings offer valuable insights into the design of highly efficient OER catalysts while also shedding light on the efficacy of LDH electrocatalysts.

Cadmium-free quantum dot light emitting devices: energy-transfer realizing pure blue emission.

In this study, deep blue, pure electroluminescence (EL) at 441.5 nm from a ZnSe/ZnS quantum dot light-emitting device (QD-LED) is obtained by using poly (4-butylphenyl-diphenyl-amine) (poly-TPD) as the hole-transport layer (HTL) to open up the channel for energy transfer from poly-TPD to QDs. The emission originating from HTL is observed in the QD-LED with N,N'-bis (tolyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine functionalized with two styryl groups (2-TPD) as the HTL due to inefficient energy-transfer from 2-TPD to QDs. The poly-TPD based device exhibits color-saturated blue emission with a narrow spectral bandwidth of full width at half maximum (~17.2 nm). These results explore the operating mechanism of the QD EL and signify a remarkable progress in deep blue QD-LEDs based on environmental-friendly QD materials.

Controlling the fluorescent properties of aqueous CdTe nanocrystals by modulating the growth rate.

Although high quality aqueous CdTe and CdTeS alloyed quantum dots (QDs) have been synthesized in recent years, the relationship between the fluorescent properties and the growth kinetics has not been well documented yet. In this paper, 3-mercaptopropionic acid stabilized aqueous CdTe nanocrystals (NCs) are generally prepared with an improvement of the "traditional" synthetic approach, where the preparation of the red emission NCs is usually time-consuming due to the slow growth rate. The investigation on the kinetic and thermodynamic growth process shows that the growth can be effectively accelerated by decreasing the ligand concentration from 0.06 to 0.01 mol/L or elevating the growth temperature from 120 to 240 degrees C. In contrast to previous results, the quantum yield (QY) of the CdTe NCs is heightened to 45% only by increasing properly the growth rate. Our experiments depict that high growth rate favours high concentration of free monomers and thus decreases the number of the surface Te atoms of the NCs, leading to the enhancement of the photoluminescence (PL) QY.

[Homogeneous phase fluorescence assay based on NaYF4 : Er3+, Yb3+ UCNPs as donors].

Upconversion nanoparticles (UCNPs) of small size have great potential in homogeneous assay based on fluorescence resonance energy transfer (FRET). A novel approach of surface ligand-exchange for preparing water-soluble and amido-functionalized NaYF4 : Er3+, Yb3+ UCNPs with 12 nm was developed. The ligand exchange process was confirmed by Fourier transform infrared spectra. Investigations by scan electron microscopy showed no obvious variations in the size and shape of the UCNPs. The circular dichroism characterization demonstrates that the secondary structure of the avidin remains largely intact after the conjugation. Avidin-biotin served as a bridge to make the short enough distance for FRET between the acceptor biotinylated R-phycoerythrin and the donors avidin-conjugated UCNPs. When the free biotins were added into this system, they competitively combined with avidin on the UCNPs surface and impede the FRET to triggered fluorescence changes. According to the relationship between this change and the addition of the amount of biotin, such FRET-based approach can reach a limit of detection in the nanomolar concentration range.

Super-stable mineralization of Cu, Cd, Zn and Pb by CaAl-layered double hydroxide: Performance, mechanism, and large-scale application in agriculture soil remediation.

The synthesized CaAl-layered double hydroxide (CaAl-LDH) shows excellent performance in potentially toxic metals (PTMs) removal, and the removal capacity of CaAl-LDH toward Cu2+, Zn2+ and Pb2+ in aqueous solution is 502.4, 315.2 and 600.0 mg/g respectively. Cu2+ and Zn2+ are removed through isomorphic substitution of laminate Ca and dissolution-reprecipitation, leading to the formation of CuAl-LDH and ZnAl-LDH mineralization products. Pb2+ is removed by the complexation and precipitation to form Pb3(CO3)2(OH)2. The application of CaAl-LDH in laboratory-scale soil remediation shows that target PTMs are gradually mineralized into relatively stable oxidizable and residual state, and the immobilization efficiency of available Cu, Zn, Cd and Pb reaches 84.62 %, 98.66 %, 96.81 % and 70.27 % respectively. In addition, practical application in farmland results in the significant reduction of available Cu, Zn, Cd and Pb with the immobilization efficiency of 30.15 %, 67.30 % and 57.80 % and 38.71 % respectively. Owing to the super-stable mineralization effect of CaAl-LDH, the content of PTMs in the roots, stems and grains of cultivated buckwheat also decreases obviously, and the growth and yield of buckwheat are not adversely affected but improved. The above prove that the super-stable mineralization based on CaAl-LDH is a promising scheme for the remediation of PTMs contaminated agriculture soil.

Photoassisted Strategy to Promote Glycerol Electrooxidation to Lactic Acid Coupled with Hydrogen Production.

Electrocatalytic oxidation of glycerol (GLY; from a biodiesel byproduct) to lactic acid (LA; the key monomers for polylactic acid; PLA) is considered a sustainable approach for biomass waste upcycling and is coupled with cathodic hydrogen (H2) production. However, current research still suffer from issues of low current density and low LA selectivity. Herein, we reported a photoassisted electrocatalytic strategy to achieve the selective oxidation of GLY to LA over a gold nanowire (Au NW) catalyst, attaining a high current density of 387 mA cm-2 at 0.95 V vs RHE, together with a high LA selectivity of 80%, outperforming most of the reported works in the literature. We reveal that the light-assistance strategy plays a dual role, which can both accelerate the reaction rate through the photothermal effect and also promote the adsorption of the middle hydroxyl of GLY over Au NWs to realize the selective oxidation of GLY to LA. As a proof-of-concept, we realized the direct conversion of crude GLY that was extracted from cooking oil to attain LA and coupled it with H2 production using the developed photoassisted electrooxidation process, revealing the potential of this strategy in practical applications.

Promoting Electrocatalytic Hydrogenation of Oxalic Acid to Glycolic Acid via an Al3+ Ion Adsorption Strategy Coupled with Ethylene Glycol Oxidation.

Electrocatalytic hydrogenation (ECH) of oxalic acid (OX) to produce glycolic acid (GA), an important building block of biodegradable polymers as well as application in various branches of chemistry, has attracted extensive attention in the industry, while it still encounters challenges of low reaction rate and selectivity. Herein, we reported a cation adsorption strategy to realize the efficient ECH of OX to GA by adsorbing Al3+ ions on an anatase titanium dioxide (TiO2) nanosheet array, achieving 2-fold enhanced GA productivity (1.3 vs 0.65 mmol cm-2 h-1) with higher Faradaic efficiency (FE) (85 vs 69%) at -0.74 V vs RHE. We reveal that the Al3+ adatoms on TiO2 both act as electrophilic adsorption sites to enhance the carbonyl (C═O) adsorption of OX and glyoxylic acid (intermediate) and also promote the generation of reactive hydrogen (H*) on TiO2, thus promoting the reaction rate. This strategy is demonstrated effective for different carboxylic acids. Furthermore, we realized the coproduction of GA at the bipolar of a H-type cell by pairing ECH of OX (at cathode) and electrooxidation of ethylene glycol (at anode), demonstrating an economical manner with maximum electron economy.

Scalable electrosynthesis of commodity chemicals from biomass by suppressing non-Faradaic transformations.

Electrooxidation of biomass platforms provides a sustainable route to produce valuable oxygenates, but the practical implementation is hampered by the severe carbon loss stemming from inherent instability of substrates and/or intermediates in alkaline electrolyte, especially under high concentration. Herein, based on the understanding of non-Faradaic degradation, we develop a single-pass continuous flow reactor (SPCFR) system with high ratio of electrode-area/electrolyte-volume, short duration time of substrates in the reactor, and separate feeding of substrate and alkaline solution, thus largely suppressing non-Faradaic degradation. By constructing a nine-stacked-modules SPCFR system, we achieve electrooxidation of glucose-to-formate and 5-hydroxymethylfurfural (HMF)-to-2,5-furandicarboxylic acid (FDCA) with high single-pass conversion efficiency (SPCE; 81.8% and 95.8%, respectively) and high selectivity (formate: 76.5%, FDCA: 96.9%) at high concentrations (formate: 562.8 mM, FDCA: 556.9 mM). Furthermore, we demonstrate continuous and kilogram-scale electrosynthesis of potassium diformate (0.7 kg) from wood and soybean oil, and FDCA (1.17 kg) from HMF. This work highlights the importance of understanding and suppressing non-Faradaic degradation, providing opportunities for scalable biomass upgrading using electrochemical technology.

Bright Tm3+-based downshifting luminescence nanoprobe operating around 1800 nm for NIR-IIb and c bioimaging.

Fluorescence bioimaging based on rare-earth-doped nanocrystals (RENCs) in the shortwave infrared (SWIR, 1000-3000 nm) region has aroused intense interest due to deeper penetration depth and clarity. However, their downshifting emission rarely shows sufficient brightness beyond 1600 nm, especially in NIR-IIc. Here, we present a class of thulium (Tm) self-sensitized RENC fluorescence probes that exhibit bright downshifting luminescence at 1600-2100 nm (NIR-IIb/c) for in vivo bioimaging. An inert shell coating minimizes surface quenching and combines strong cross-relaxation, allowing LiTmF4@LiYF4 NPs to emit these intense downshifting emissions by absorbing NIR photons at 800 nm (large Stokes shift ~1000 nm with a absolute quantum yield of ~14.16%) or 1208 nm (NIR-IIin and NIR-IIout). Furthermore, doping with Er3+ for energy trapping achieves four-wavelength NIR irradiation and bright NIR-IIb/c emission. Our results show that Tm-based NPs, as NIR-IIb/c nanoprobes with high signal-to-background ratio and clarity, open new opportunities for future applications and translation into diverse fields.

CaGdF5 based heterogeneous core@shell upconversion nanoparticles for sensitive temperature measurement.

Lanthanide-doped upconversion nanoparticles (UCNPs) have attracted great attention in temperature sensing because of their widespread thermal quenching effect (TQE), a phenomenon in which luminescence intensity decreases as the temperature increases. However, enhancing the TQE of activated ions without changing the dopants or the host is still challenging. Herein, Yb3+ and Er3+ codoped UCNPs in a cubic CaGdF5 host were synthesized by a coprecipitation method for optical temperature sensing. Compared with the homogeneous shell (CaGdF5), those heterogeneous (CaF2) shelled UCNPs exhibited stronger upconversion luminescence (UCL) due to the significantly reduced multiphonon nonradiative relaxation. Further, we investigated the effects of homogeneous and heterogeneous shells on TQE. The relationship between the intensity ratio of the green emission bands of Er3+ ions (2H11/2 → 4I15/2 and 4S3/2 → 4I15/2) and temperature are obtained for these two core@shell UCNPs. The results demonstrated that the UCNPs with CaF2 shells are more sensitive to temperature in the 200-300 K. The maximum thermal sensitivity of CaGdF5:Yb,Er@CaF2 could reach 2.2% K-1 at 200 K. These results indicate that the heterogeneous core@shell UCNPs are promising for use as optical temperature sensors.

Alcohols electrooxidation coupled with H2 production at high current densities promoted by a cooperative catalyst.

Electrochemical alcohols oxidation offers a promising approach to produce valuable chemicals and facilitate coupled H2 production. However, the corresponding current density is very low at moderate cell potential that substantially limits the overall productivity. Here we report the electrooxidation of benzyl alcohol coupled with H2 production at high current density (540 mA cm-2 at 1.5 V vs. RHE) over a cooperative catalyst of Au nanoparticles supported on cobalt oxyhydroxide nanosheets (Au/CoOOH). The absolute current can further reach 4.8 A at 2.0 V in a more realistic two-electrode membrane-free flow electrolyzer. Experimental combined with theoretical results indicate that the benzyl alcohol can be enriched at Au/CoOOH interface and oxidized by the electrophilic oxygen species (OH*) generated on CoOOH, leading to higher activity than pure Au. Based on the finding that the catalyst can be reversibly oxidized/reduced at anodic potential/open circuit, we design an intermittent potential (IP) strategy for long-term alcohol electrooxidation that achieves high current density (>250 mA cm-2) over 24 h with promoted productivity and decreased energy consumption.

Insights into the Superstable Mineralization of Chromium(III) from Wastewater by CuO.

The removal of CrIII ions from contaminated wastewater is of great urgency from both environmental protection and resource utilization perspectives. Herein, we developed a superstable mineralization method to immobilize Cr3+ ions from wastewater using CuO as a stabilizer, leading to the formation of a CuCr layered double hydroxide (denoted as CuCr-LDH). CuO showed a superior Cr3+ removal performance with a removal efficiency of 97.97% and a maximum adsorption capacity of 207.6 mg/g in a 13000 mg/L Cr3+ ion solution. In situ and ex situ X-ray absorption fine structure characterizations were carried out to elucidate the superstable mineralization mechanism. Two reaction pathways were proposed including coprecipitation-dissolution and topological transformation. The mineralized product of CuCr-LDH can be reused for the efficient removal of organic dyes, and the adsorption capacities were up to 248.0 mg/g for Congo red and 240.1 mg/g for Evans blue, respectively. Moreover, CuCr-LDH exhibited a good performance for photocatalytic CO2 reduction to syngas (H2/CO = 2.66) with evolution rates of 54.03 µmol/g·h for CO and of 143.94 µmol/g·h for H2 under λ > 400 nm, respectively. More encouragingly, the actual tanning leather Cr3+ wastewater treated by CuO showed that Cr3+ can reduce from 3438 to 0.06 mg/L, which was much below discharge standards (1.5 mg/L). This work provides a new approach to the mineralization of Cr3+ ions through the "salt-oxide" route, and the findings reported herein may guide the future design of highly efficient mineralization agents for heavy metals.