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Development of efficient photocatalytic hydrogen evolution reaction (HER) with illumination of visible light is challenging. In this work, five chlorophyll derivatives (M-Chls; M = H2/Cu/Ni/Co/Zn) with different central ions in its cyclic tetrapyrrole ring including free base, copper, nickel, cobalt, and zinc were synthesized and employed as the effective visible-light harvester for efficient HER. In addition, two-dimensional (2D) noble metal-free co-catalyst Ti3C2Tx MXene was used as an excellent electron capturer due to its outstanding conductivity property. These M-Chls are modified on the surface of Ti3C2Tx MXene with 2D accordion-like morphology by means of a simple deposition process to form noble metal-free Chl/Ti3C2Tx-based photocatalysts for HER. It is found that the best HER performance as high as 49 μmol/h/gcat was achieved with the Co-Chl@Ti3C2Tx hybrid, which was much higher than those of other M-Chl@Ti3C2Tx composites. This research provides a specific way to synthesize low-cost and environmentally friendly natural Chls for developing highly efficient photocatalytic HER through molecular engineering.

The Z-scheme process is a photoinduced electron-transfer pathway in natural oxygenic photosynthesis involving electron transport from photosystem II (PSII) to photosystem I (PSI). Inspired by the interesting Z-scheme process, herein a photocatalytic hydrogen evolution reaction (HER) employing chlorophyll (Chl) derivatives, Chl-1 and Chl-2, on the surface of Ti3 C2 Tx MXene with two-dimensional accordion-like morphology, forming Chl-1@Chl-2@Ti3 C2 Tx composite, is demonstrated. Due to the frontier molecular orbital energy alignments of Chl-1 and Chl-2, sublayer Chl-1 is a simulation of PSI, whereas upper layer Chl-2 is equivalent to PSII, and the resultant electron transport can take place from Chl-2 to Chl-1. Under the illumination of visible light (>420 nm), the HER performance of Chl-1@Chl-2@Ti3 C2 Tx photocatalyst was found to be as high as 143 μmol h-1 gcat-1 , which was substantially higher than that of photocatalysts of either Chl-1@Ti3 C2 Tx (20 μmol h-1 g-1 ) or Chl-2@Ti3 C2 Tx (15 μmol h-1 g-1 ).

A self-designed mini gas–solid reaction device was applied as promising equipment to investigate the oxidation characteristics and kinetics of the glycerol ester of rosin (GER) under 254 nm UV irradiation in air. Peroxide formation during the photo-oxidation process was analyzed by iodimetry. The peroxide concentration is related to the light intensity (I) and the temperature (T), and increasing I and T would destabilize the GER by accelerating peroxide generation. The photo-oxidation of GER followed pseudo-first-order reaction kinetics under a given hypothesis. A linear relationship was observed between activation energy and the logarithm of light intensity (ln I), which can be expressed as Ea = −3.575 ln I + 34.943 under the experimental conditions. This research indicated that under 254 nm UV irradiation GER could be easily oxidized even at room temperature.

The thermal oxidation characteristics of abietic acid were investigated through tracing the oxidation process in custom-designed mini closed pressure vessel test under isothermal and step temperatu...

In this work, thermal oxidation reaction of dimethoxymethane (DMM) at low temperature was investigated with a custom-designed mini closed pressure vessel test (MCPVT) employed. The initial auto-oxidation, thermal decomposition and deep radical oxidation processes were revealed by analyzing the behavior of oxidation temperature (T) and pressure (P) in the process of MCPVT monitoring. Peroxides generated from DMM auto-oxidation were measured by iodimetry and thin-layer chromatography (TLC). The dominant peroxide was separated from oxidation products via column chromatography, with structure characterized by mass spectrometry (MS), 1H and 13C nuclear magnetic resonance (NMR). The thermal decomposition characteristics were determined by differential scanning calorimeter (DSC). Results show that the oxidation was mainly initiated by hydrogen abstraction on the methylenedioxy (O-CH2-O) of DMM when temperature was above about 310 K. The primary product of hydroperoxide, hydroperoxy(methoxymethoxy)methane was found in DMM oxidation for the first time, with a high level. Its exothermic onset temperature (T0) and decomposition heat (QDSC) are 372.87 K and 2431.37 J·g−1, respectively. The thermal decomposition could lead to thermal runaway of oxidation, and further transform into an explosion. In most cases, the release of radical pool after peroxides decomposition would induce a rapidly radical oxidation of DMM through an endothermic reaction at about 410 K.

Carbon-based solid acid catalysts were prepared using rice straw (RS) waste, and the effects of carbonization temperature and sulfonation temperature on the catalytic activity were investigated. The properties of the catalysts were characterized using thermo gravimetric (TG), scanning electron microscope (SEM), Brunauer&ndash, Emmet&ndash, Teller (BET), Fourier transform infrared spectroscopy (FT-IR), temperature-programmed desorption (TPD), and X-ray photoelectron spectroscopy (XPS), and their activities were investigated through the hydration of &alpha, pinene. The conversion of &alpha, pinene and the selectivity of &alpha, terpineol reached 67.60% and 57.07% at 80 &deg, C and atmospheric pressure in 24 h, respectively. The high catalytic capacity of the catalyst is attributed to the high acid site density and high porosity of the catalyst. TPD analysis and FT-IR spectroscopy showed that the catalyst produced by low-temperature carbonization at 300 &deg, C followed by low-temperature sulfonation at 80 &deg, C had abundant strong acid sites (0.82 mmol/g), which can effectively inhibit the side reactions of hydrated &alpha, pinene. The total acidity reached 2.87 mmol/g. N2-physisorption analysis clearly indicated that the obtained catalysts were mesopore-predominant materials, and the SBET and VTotal of catalysts reached 420.9 m2/g and 4.048 cm3/g,, respectively. Preparation of the catalyst involves low energy consumption, and its cheap raw materials make the whole process simple, economical, and environmentally friendly.

Pressure and temperature behavior of the cinnamaldehyde oxidation process was determined using a custom-designed mini closed pressure vessel test (MCPVT), which is a new method to investigate the stability and hazard assesment of the cinnamaldehyde oxidation reaction. The oxidation products were analyzed by gas chromatography-mass spectrometry (GC-MS). The results showed that cinnamaldehyde was stable under nitrogen atmosphere but very unstable under oxygen atmosphere. The initial oxidation products were analyzed by iodimetry and the cinnamaldehyde peroxide value could reach 139.44 mmol kg−1 when the oxidation temperature was 308 K. The oxidation kinetics of cinnamaldehyde were studied by using the pressure versus time (P–t) curves obtained from the MCPVT process. The reaction is a second-order reaction, the kinetic equation is ln k = −2233.66 × (1/T) + 11.19, and the activation energy Ea is 18.57 kJ mol−1 at 308–338 K. The explosion of the cinnamaldehyde oxidation reaction was observed by MCPVT, in which the onset temperature was 373 K. The main products of cinnamaldehyde oxidation are acetaldehyde, benzaldehyde, phenylacetaldehyde, acetophenone, 2-hydroxyphenyl acetone, cinnamaldehyde epoxide, benzoic acid, and cinnamic acid. Oxidation is a three-step process: (1) cinnamaldehyde reacts with oxygen to form peroxides; (2) complex oxidation reactions are caused by the thermal decomposition of peroxides; (3) rapid oxidation and thermal decomposition lead to explosion hazard.

Chlorophylls (Chls) are the most abundant natural pigments having excellent opt-electrical and semi-conductive properties. Ti3C2Tx MXene, one of the most extensively studied 2D noble metal-free co-catalyst, features outstanding electrochemical properties. This work compares three aggregate-forming chlorophyll derivatives (Chl-n; n = 1–3), namely, zinc methyl 3-devinyl-3-hydroxymethyl-pyropheophorbide-a (Chl-1), zinc dodecyl 3-devinyl-3-hydroxymethyl-pyropheophorbide-a (Chl-2) and zinc dodecyl 131-deoxo-3-devinyl-131-dicyanomethylene-3-hydroxymethyl-pyropheophorbide-a (Chl-3), as light-harvesting antenna pigments in the MXene-based photocatalytic system for hydrogen evolution under the white light illumination (λ > 420 nm). The hydrogen evolution reaction (HER) of these Chls depends on the peripheral substituent groups at the C13- and/or C17-positions of the chlorin macrocyclic π-system. Differences among these Chl-n sensitized Ti3C2Tx MXene (Chl-n@Ti3C2Tx) are compared in terms of their light-harvesting ability, morphology, charge transfer efficiency and photocatalytic performance. The best HER performance is found to be as high as 122 μmol/h/gcat with the Chl-3@Ti3C2Tx composite. This work leads the direction in synthesizing Chls in Chl/MXene hybrid structure suitable for highly efficient photocatalytic HER.

The initial electrical properties of tantalum oxide resistive memory were investigated using four metal electrodes (TiN, Ti, Ta, and Al) and two kinds of tantalum oxide with different amounts of intrinsic oxygen vacancies. The initial resistance depended on the electrode material. This indicated that oxygen scavenging by the electrodes contributed to a reduction in the resistance. However, the resistance change depended on the intrinsic oxygen vacancy concentration introduced during the tantalum oxide deposition. The forming voltage also depended on the electrode metal. For the device with an Al electrode, a clear aluminum oxide layer was identified at the electrode–insulator interface, which was hypothesized to be the origin of the high forming voltage. All factors concerning the oxygen vacancies, i.e. intrinsic vacancies introduced via film deposition and extrinsic vacancies caused by the electrode scavenging effect, influenced the initial state of tantalum oxide, and thus, its switching performance as a resistive memory.

In this study, silicoaluminophosphate (SAPO)-34 and Me (Me = Cr, Co)-modified SAPO-34 were synthesized and used as catalysts to investigate the catalytic performance by means of a probe reaction from ethanol to ethylene. The metal oxides were loaded on the SAPO-34 support via an impregnation method. The synthesized catalysts were characterized using XRD, SEM, EDX, FT-IR, NH3-TPD, BET, and TGA techniques. Compared to SAPO-34, SAPO-34 doped with metal oxides showed the same chabazite (CHA) topology. The structure and properties of the catalyst were further optimized by varying the amount of Me. The experimental results showed that Co-Cr/SAPO-34 exhibited the best catalytic performance when the reaction temperature reached 400 &deg, C at a weight hourly space velocity (WHSV) of 3.5 h&minus, 1, for which the single-pass conversion of ethanol was determined as 99.15%, and the selectivity of ethylene was 99.4% at an optimum catalytic performance in the reaction of up to 600 min. In addition, Co-Cr/SAPO-34 exhibited better catalytic activity and anti-coking ability than pure SAPO-34, which was attributed to its enhanced pore structure and moderate acidity. It can also be concluded from the results of this experiment that the performance of the Co-Cr bimetal-supported catalyst is better than that of the Cr mono-metal catalyst.

Efficient photocatalytic hydrogen evolution reaction (HER) in the visible‐to‐near infrared region at a low cost remains a challenging issue. This work demonstrates the fabrication of organic‐inorganic composites by deposition of supramolecular aggregates of a chlorophyll derivative, namely, zinc methyl 3‐devinyl‐3‐hydroxymethyl‐pyropheophorbide a (Chl) on the surface of Ti3C2Tx MXene with 2D accordion‐like morphology. This composite material is employed as noble metal‐free catalyst in photocatalytic HER under the white light illumination, where Chl serves as a small molecule organic semiconductor component instead of ordinary inorganic and polymer organic semiconductors such as TiO2 and g‐C3N4, and Ti3C2Tx serves as a co‐catalyst. Different composition ratios of Chl/Ti3C2Tx are compared for their light‐harvesting ability, morphology, charge transfer efficiency, and photocatalytic performance. The best HER performance is found to be as high as 52 ± 5 µmol h−1 gcat−1 after optimization. Such a large HER activity is attributed to the efficient light harvesting followed by exciton transfer in Chl aggregates and the resultant charge separation at the interface of Chl/Ti3C2Tx.

A self-designed reaction device was used as a promising equipment to investigate the oxidation characteristics and kinetics of rosin pentaerythritol ester (RPE) under UV irradiation. Photo-oxidation kinetics and the initial quantum yield (&Phi, ) of RPE were calculated. The initial oxidation product of the photo-oxidation reaction&mdash, peroxide was analyzed by iodimetry. The peroxide concentration is related to the light intensity (I) and the temperature (T), and the increasing T and I would destabilize the RPE by accelerating peroxide forming. Photo-oxidation of RPE follows the pseudo first-order reaction kinetics. The relationship between activation energy and logarithm of light intensity (ln I) is linear, and it is expressed as Ea = &minus, 4.937ln I + 45.565. &Phi, was calculated by the photo-oxidation kinetics, and the average value of &Phi, was 7.19% in the light intensity range of 200&ndash, 800 &mu, W cm&minus, 2. This research can provide fundamental information for application of RPE, and help obtain a better understanding of the stability of rosin esters.

Polymeric micelles are important nanovehicles for anticancer drug delivery. The lipophilic segment in polymeric micelles is an important factor to affect the drug loading properties. In our previous work, we found that small molecules with π-π conjugated structures could be used to replace hydrophobic polymeric chains as lipophilic segments for anticancer drug delivery. Herein, we report a novel polymeric micelle with π-π conjugated cinnamate moiety on glycerol dendrimer as lipophilic segment, the modified dendritic segment was connected to poly(ethylene glycol) (PEG) via click chemistry. The received amphiphiles self-assembled into micelles in aqueous medium. The properties of the polymeric micelles such as critical micelle concentration (CMC), mean size and morphology were investigated. Anticancer drug doxorubicin (DOX) was loaded in the polymeric micelles. The π-π interaction, drug release profile and in vitro anticancer efficiency of the DOX loaded micelles were studied. The results showed that the micelles with more cinnamate moieties exhibited a lower CMC. The drug loading content and release rate of the micelles increased with increasing generation of glycerol dendrimer. Strong π-π stacking interaction was detected between DOX and carriers. The DOX loaded polymeric micelles exhibited efficient anticancer activity in vitro.

Biodegradable poly(L-lactide-r-trimethene carbonate) copolymers (P(LLA-co-TMC)) with different compositions were synthesized. The degradation of the copolymers was carried out in phosphate buffer saline solutions (pH = 7.4) at 37 °C. The compositions, structure and properties of the copolymers in degradation were characterized with 1H-NMR, DSC, XRD, GPC, and SEM. The weight loss of the P(LLA-co-TMC) 50/50 was much faster than that of P(LLA-co-TMC) 85/15 and PLLA homopolymer. Interestingly, though the molecular weight of the compolymers decreased greatly during degradation, the compositions were rarely varied. After long time degradation, the PLLA segments were induced to crystallize in the P(LLA-co-TMC) 85/15 copolymer. The SEM observation of the surface and cross-section of P(LLA-co-TMC) 85/15 copolymer films found it was similar to the bulk degradation of PLLA homopolymer.

In this context, the differential mass conservation equations were used to describe typical noncatalytic gas–solid reactions, such as biomass chars gasification, and an approximate method was appli...

Herein, we reported a new type of self-assembly micelles based on amphiphilic polymers of cinnamate and coumarin derivatives modified PEG for drug delivery applications. Lipophilic cinnamic acid (CIN) and 7-carboxyl methoxycoumarin (COU) were immobilized on the terminal groups of poly(ethylene glycol) (PEG) to prepare amphiphiles. The amphiphiles self-assembled into micelles. The amphiphiles and micelles were characterized by (1)H NMR, FT-IR, DLS and TEM. Doxorubicin (DOX) was used as a model drug to investigate the lipophilic moieties effects on the drug release behaviors. The DOX loaded micelles were incubated with HepG2 liver cancer cells to study the in vitro anticancer activities. The results showed that DOX could be encapsulated in the micelles efficiently. The mean diameter of the drug loaded micelles was around 100 nm. Drug release profile revealed that the release rate of DOX loaded COU-PEG-COU micelles was significantly slower than that of CIN-PEG-CIN micelles. The DOX loaded micelles could be internalized in HepG2 cells. Both CLSM and flow cytometry results showed that the DOX loaded CIN-PEG-CIN micelles exhibited better anticancer efficacy.

We summarize recent results on reversible group rings, duo group rings, and graded reversible group rings; and we mention several open problems.

In this paper, π-π conjugated cinnamic acid (CIN) was used as a lipophilic moiety to fabricate polymeric micelles. The amphiphiles with one or two cinnamic acid molecules as lipophilic architectures (mPEG-CIN and mPEG-Lys-DCIN) were synthesized. We expressly investigated the effect of the lipophilic parts on size, morphology and stability of the self-assembly micelles. Anticancer drug doxorubicin (DOX) was trapped in the micelles and the interactions between the lipophilic moieties and DOX were studied. The anticancer activity of the DOX-loaded micelles was evaluated both in vitro and in vivo. The results revealed that mPEG-Lys-DCIN micelles exhibited better stability and higher drug loading content. Strong π-π stacking interaction was formed within the DOX-loaded micelles. The DOX released from mPEG-Lys-DCIN micelles was slower than that from mPEG-CIN micelles. DOX-loaded mPEG-Lys-DCIN micelles exhibit higher inhibition efficiency both in vitro and in vivo. Furthermore, the in vivo experimental results demonstrated that the anticancer efficiency of DOX-loaded mPEG-Lys-DCIN micelles was comparable to that of free DOX, meanwhile, the side effect of DOX was reduced greatly after encapsulation. This novel strategy of fabricating polymeric micelles with π-π conjugated small molecules as lipophilic moieties could be serve as a universal prototype for drug delivery.