Synergistic effects of nano-structured WO3-Se heterojunction decorated by organic Nafion layer on improving photoelectrochemical performance.

Exploration of high-performance photoanodes is considered as an essential challenge in photoelectrochemical (PEC) water splitting due to the complex four-electron reaction in water oxidation. Herein, the nano-structured WO3-Se heterojunction decorated by organic Nafion layer is designed. The optimized WO3-Se200-0.05Nafion photoanode shows a remarkable photocurrent of 1.40 mA cm-2at 1.23 V versus reversible hydrogen electrode, which is 2.5-fold higher than that of pure WO3nanosheets (WO3NS) photoelectrode. Remarkably, the photocurrent increments of WO3-Se200-0.05Nafion is larger than the increment sum of WO3-Se200 and WO3-0.05Nafion, which affirming the synergistic effect of Se nanospheres and Nafion layer. The improved PEC performances are attributed to the quick charge separation and transfer, the increased electric conductivity, and the excellent kinetics of oxygen evolution, which is derived from the strong interaction among WO3, Se and Nafion. Meanwhile, the better visible-light harvesting from Se nanospheres as photosensitizer and the induction of transparent Nafion as a passivation layer can explain this synergy. It hopes this heterostructure design with organic Nafion decoration can inspire to exploit outstanding performance photoanodes for PEC water splitting.

Cooperative effect of bimetallic MOF-derived CoNi(OH)2@NiCo2S4nanocomposite electrocatalysts with boosted oxygen evolution activity.

Highly efficient and inexpensive electrocatalysts for oxygen evolution reaction (OER) are extensively studied for water splitting. Herein, a unique bimetallic nanocomposite CoNi(OH)2@NiCo2S4nanosheet arrays derived from metal-organic-frameworks (MOFs, CoNi-ZIF) is simply fabricated on Ni foam, endowing large specific surface area and outstanding electrical conductivity. Compared with their single-metallic counterparts, the bimetallic composite displays dramatically low overpotential and small Tafel slope as well as outstanding catalytic stability. The overpoptential at 20 mA cm-2for CoNi(OH)2@NiCo2S4is only 230 mV in comparison with Ni(OH)2@Ni3S2(266 mV), Co(OH)2@Co3S4(294 mV) and RuO2(η = 302 mV). First-principle calculations based on density functional theory (DFT) are carried out and reveal that the introduction of Ni in Co(OH)2helps lowered the energy difference of ΔGOOH*-ΔGO*, and thereby boosting the OER reactivity. This study provides an effective approach for the rational construction of low-cost metal hybrids.

Optimization of Electrochemical Reduction of Biomass Derived 5-Hydroxymethylfurfural (HMF): A Volcano Plot and Bimetallic Catalysts.

2,5-bis(hydroxymethyl)furan (BHMF) derived from 5-Hydroxymethylfurfural (HMF) through a hydrogenation process has extensive applications in the production of resins, polymers, and artificial fibers. However, screening out the candidate and then modulating the active site to optimize the catalyst for high yield of BHMF are currently insufficient. In this study, Gibbs free energy diagrams of the reduction of HMF on 13 metals were presented, along with the identification of the rate-determining step (RDS) with the highest reaction barrier for each metal. We attempted to construct a volcano plot for HMFRR reaction. Additionally, a strategy was proposed to adjust the reaction barriers of RDS by combining two appropriate metals. Further experiments confirmed that Pb with the lowest energy barrier exhibited the highest HMF conversion (BHMF selectivity) among single metals. The modified catalyst by doping Ag on Pb, further boosted the HMF conversion (BHMF selectivity) from 42.1 % (59.4 %) to 80.8 % (80.9 %), respectively. These results provide an approach to rationally design and construct the catalyst system for efficient conversion of HMF.

Palladium-based pseudohomogeneous catalyst for highly selective aerobic oxidation of benzylic alcohols to aldehydes.

This study presents a novel class of pseudohomogeneous catalysts (PHC) based on carbon quantum dots functionalized with terpyridine ligands (CQDs-Tpy) to immobilize and stabilize palladium nanoparticles (Pd NPs). Extensive characterization techniques clearly confirmed the successful stabilization of Pd NPs on CQDs-Tpy. The effectiveness of the catalyst was demonstrated in the selective aerobic oxidation of primary and secondary of benzylic alcohols to aldehydes in the absence of additives and phase transfer catalyst (PTC). Remarkably, the reactions predominantly yielded aldehydes without further oxidation to carboxylic acids. By employing low catalyst loadings (0.13 mol%), high conversions (up to 89%) and excellent selectivity (> 99%) of the aldehyde derivatives were achieved. Moreover, the CQDs-Tpy/Pd NPs catalyst displayed suitable catalytic activity and recyclability, offering potential economic advantages. This promising approach opens up new opportunities in the field of catalysis for designing subnanometric metal-based PHCs.

Introducing Fe into Cu-based catalyst to boost the electrocatalytic hydrogenation of 5-hydroxymethylfurfural.

Converting biomass-derived 5-hydroxymethylfurfural (HMF) into high-valued 2,5-bis (hydroxymethyl)furan (BHMF) via electrocatalytic hydrogenation (ECH) technology has been widely regarded as one of the most economical and eco-friendly routes. The high selectivity and activity depend on the reasonable regulation of the adsorption and activation of adsorbed hydrogen (H*) and HMF on the surface of the electrocatalyst. Herein, we report nanoflower-like CuFe-based electrocatalysts on copper foam (CF) substrates (CuFeOx/CF). BHMF was achieved on the optimal CuFeOx/CF with a selectivity of 93.3% and a yield of 90.1%. The H*, HMF and product were observed by in situ attuned total reflection Fourier transform infrared spectroscopy (ATR-FTIR). Moreover, in situ Raman spectra discloses the reconstruction of catalyst into CuFe-bimetal with low valence state. Density functional theory (DFT) calculations demonstrate that introducing Fe plays a role in regulating the electronic structure of Cu sites, which facilitate the generation of H* and adsorption of HMF, thus hampering the occurrence of dimerization. This study provides an innovative idea for the rational design of non-precious bimetallic electrocatalysts for ECH to produce high-valued chemicals.

Photocatalytic removal of imidacloprid pesticide from wastewater using CdS QDs passivated by CQDs containing thiol groups.

Over the past decade, CdS QDs have become versatile semiconductors. Surface modification of CdS QDs has become an interesting case study, as it can eliminate surface defects and improve their photochemical properties. In this study, we report a new strategy of using carbon quantum dots containing a large number of thiol groups (CQDs-SH) as a passivating agent for the stabilization of CdS quantum dots (QDs). Various characterization techniques have clearly revealed that the CdS QDs have been successfully passivated by CQDs-SH. The photocatalytic performance of CQDs-SH/CdS QDs was investigated for the degradation of the insecticide imidacloprid from an aqueous solution. Parameters affecting the photodegradation process, including the light source, photocatalyst amount, initial concentration of the pollutant, radiation time, pH, oxidizing agent, and temperature, were investigated. Furthermore, the HPLC technique was applied to quantitatively analyze imidacloprid and its degradation products. The results of the HPLC analysis revealed that under simulated visible light at pH 9, imidacloprid scarcely existed after 90 min of irradiation (90.13% degradation). The LC-MS method was also used to detect the degradation products and investigate the mechanism of photodegradation of the pesticide. The results showed that the CQDs-SH/CdS QDs composite was a promising photocatalyst for the degradation of imidacloprid in wastewater.

Full-Scale Measurements of Translational and Torsional Dynamics Characteristics of a High-Rise Building during Typhoon Sarika.

The field measurement of wind-induced response is of great significance to the wind resistance design of high-rise buildings, in particular torsional responses measured from high-rise buildings under typhoons. The measured high-rise building, with a height of 108 m, has 32 stories and is supported by giant trusses with four massive columns. Acceleration responses along translational and torsional directions were monitored synchronously and continuously during the passage of Typhoon Sarika on 18 October 2016. The wind speed and wind direction at the height of 115 m, the translational accelerations on a total of six floors and the angular accelerations on a total of four floors were recorded. The time and frequency domain characteristics of translational acceleration and torsional angular accelerations were analyzed. The amplitude-dependent translational and torsional modal frequencies of the measured building were identified by NExT-ERA, SSI, and RDT methods. The full-scale study is expected to provide useful information on the wind-resistant design of high-rise buildings in typhoon-prone regions.

Assessment of recycling methods and processes for lithium-ion batteries.

This review discusses physical, chemical, and direct lithium-ion battery recycling methods to have an outlook on future recovery routes. Physical and chemical processes are employed to treat cathode active materials which are the greatest cost contributor in the production of lithium batteries. Direct recycling processes maintain the original chemical structure and process value of battery materials by recovering and reusing them directly. Mechanical separation is essential to liberate cathode materials that are concentrated in the finer size region. However, currently, the cathode active materials are being concentrated at a cut point that is considerably greater than the actual size found in spent batteries. Effective physical methods reduce the cost of subsequent chemical treatment and thereafter re-lithiation successfully reintroduces lithium into spent cathodes. Some of the current challenges are the difficulty in controlling impurities in recovered products and ensuring that the entire recycling process is more sustainable.

TiO2@PDA inorganic-organic core-shell skeleton supported Pd nanodots for enhanced electrocatalytic hydrodechlorination.

The development of catalysts with high atom utilization and activity is the biggest challenge for electrocatalytic hydrodechlorination (EHDC) technology. Herein, a design strategy of TiO2@PDA inorganic-organic core-shell skeleton for loading lower dosage of noble palladium (Pd) with robust activity is reported. The self-supported TiO2@PDA nanorod arrays provides exposed surface area for anchoring Pd and PDA as interlayer controls the Pd nucleation to form nanodots with high dispersion, realizing high atom utilization. Moreover, the strong interaction between PDA and Pd realizes the coexistence of electron-rich and deficient Pd species with suitable proportion, which facilitate the H* formation and the C-Cl bond activation, respectively, resulting in the promoted activity. The optimal TiO2@PDA/Pd electrode exhibits a low dosage of Pd (0.093 mg cm-2) and excellent activity for 4-chlorophenol reduction with a mass activity (MA) of 23.96 min-1g-1, which is 3.31 times as high as that of TiO2/Pd. The design scheme with inorganic-organic core-shell skeleton as support is benefit for developing highly efficient and lower price elctrocatalysts for EHDC.

Crystal Facet-Modulated WO3 Nanoplate Photoanode for Photoelectrochemical Glyoxal Semi-oxidation into Glyoxylic Acid.

Transforming glyoxal to value-added glyoxylic acid (GA) is highly desirable but challenging due to the uncontrollable over-oxidation. In this work, we report on a first demonstration of semi-oxidation of glyoxal with high selectivity (86.5%) and activity on WO3 nanoplate photoanode through the photoelectrochemical strategy. The optimization of reactivity was achieved via crystal facet regulation, showing a satisfactory GA production rate of 308.4 mmol m-2 h-2, 84.0% faradaic efficiency, and 4.3% total solar-to-glyoxylic acid efficiency on WO3 with enriched {200} facets at 1.6 V versus RHE. WO3 with a high {200} facet ratio exhibits more efficient electron-hole transfer kinetics, resulting in the facilitated formation of hydroxyl radicals (•OH) and glyoxal radicals. Meanwhile, the theoretical calculation results indicate that the high selectivity and activity come from the strong adsorption ability for glyoxal and the low reaction energy for glyoxal radical generation on the (200) facets of WO3. Moreover, the high energy demand toward oxalic acid production on WO3 leads to the exciting semi-oxidation process.