The photocatalytic CO2 reduction reaction (CRR) represents a promising route for the clean utilization of stranded renewable resources, but poor selectivity resulting from the competing hydrogen ...evolution reaction (HER) in aqueous solution limits its practical applicability. In the present contribution a photocatalyst with hydrophobic surfaces was fabricated. It facilitates an efficient three‐phase contact of CO2 (gas), H2O (liquid), and catalyst (solid). Thus, concentrated CO2 molecules in the gas phase contact the catalyst surface directly, and can overcome the mass‐transfer limitations of CO2, inhibit the HER because of lowering proton contacts, and overall enhance the CRR. Even when loaded with platinum nanoparticles, one of the most efficient HER promotion cocatalysts, the three‐phase photocatalyst maintains a selectivity of 87.9 %. Overall, three‐phase photocatalysis provides a general and reliable method to enhance the competitiveness of the CRR.
A photocatalytic CO2 reduction reaction (CRR) in aqueous solution is a promising reaction route, while severe H2 generation (HER) greatly limits its selectivity and activity. A strategy to obtain a three‐phase contact of CO2 (gas), H2O (liquid) and catalyst (solid) is described to overcome the mass transfer limitation of CO2, elevate the CO2 concentration on the catalyst surface, restrain the HER, and enhance the activity and selectivity of the CRR.
Wheat (
Triticum aestivum L.) and corn (
Zea mays L.) rotation system is important for food security in the Loess Plateau of China. Grain yield and water-use efficiency (WUE: grain yield per unit of ...water consumed) trends, and changes in soil properties during a 24-year fertilization experiment in Pingliang, Gansu, China, were recorded. Mean yields of wheat for the 16 years started in 1981 ranged from 1.29
t
ha
−1 for the unfertilized plots (CK) to 4.71
t
ha
−1 for the plots that received manure (M) annually with inorganic nitrogen (N) and phosphorus (P) fertilizers (MNP). Corn yields for the 6 years started in 1979 averaged 2.29 and 5.61
t
ha
−1 in the same treatments. Yields and WUEs declined significantly with lapse of time except CK and MNP for wheat. Wheat yields with the N and M declined at rate of 77 and 81
kg
ha
−1
year
−1, but the decline of 57
kg
ha
−1
year
−1 for NP was similar to that of 61
ha
−1
year
−1 for straw with N annually and P every second year (SNP). Likewise, the corn yields and WUEs declined from 160 to 250
kg
ha
−1
year
−1 and from 0.01 to 0.03
kg
m
−3
year
−1 among treatments, respectively. These declines were likely to loss of soil fertility and gradual dry weather. Yields were significantly correlated with seasonal evapotranspiration with slopes ranging from 0.5 to 1.27
kg
m
−3 for wheat and from 1.15 to 2.03
kg
m
−3 for corn. Soil organic carbon (SOC), total N (TN), and total P (TP) gradually built up with time except the CK, in which TN and TP remained unchanged but SOC and available P (AP) decreased. Soil AP decreased in the N. Soil available K declined rapidly without straw or manure. Balanced fertilization should be encouraged to ensure sustainable productivity in this intensive cropping system. The greatest SOC increases of about 160
mg
ha
−1
year
−1 occurred in the SNP and MNP, suggesting that long-term additions of organic materials to soil could increase soil water-holding capacity which, in return, improves water availability to plants and arrests yield declines, and decrease CO
2 emission from agricultural soils and sustain land productivity.
Electrocatalysts with single metal atoms as active sites have received increasing attention owing to their high atomic utilization efficiency and exotic catalytic activity and selectivity. This ...review aims to provide a comprehensive summary on the recent development of such single-atom electrocatalysts (SAECs) for various energy-conversion reactions. The discussion starts with an introduction of the different types of SAECs, followed by an overview of the synthetic methodologies to control the atomic dispersion of metal sites and atomically resolved characterization using state-of-the-art microscopic and spectroscopic techniques. In recognition of the extensive applications of SAECs, the electrocatalytic studies are dissected in terms of various important electrochemical reactions, including hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), carbon dioxide reduction reaction (CO2RR), and nitrogen reduction reaction (NRR). Examples of SAECs are deliberated in each case in terms of their catalytic performance, structure–property relationships, and catalytic enhancement mechanisms. A perspective is provided at the end of each section about remaining challenges and opportunities for the development of SAECs for the targeted reaction.
Changes in grain yields and soil organic carbon (SOC) from a 26 y dryland fertilization trial in Pingliang, Gansu, China, were recorded. Cumulative C inputs from straw and root and manure for ...fertilizer treatments were estimated. Mean wheat (Triticum aestivum L.) yields for the 18 y ranged from 1.72 t ha⁻¹ for the unfertilized plots (CK) to 4.65 t ha⁻¹ for the plots that received manure (M) annually with inorganic N and P fertilizers (MNP). Corn (Zea mays L.) yields for the 6 y averaged 2.43 and 5.35 t ha⁻¹ in the same treatments. Yields declined with year except in the CK for wheat. Wheat yields for N only declined with time by 117.8 kg ha⁻¹ y⁻¹ that was the highest decrease among all treatments, and that for NP declined by 84.7 kg ha⁻¹ y⁻¹, similar to the declines of 77.4 kg ha⁻¹ y⁻¹ for the treatment receiving straw and N annually and P every second year (SNP). Likewise, the corn yields declined highly for all treatments, and the declined amounts ranged from 108 to 258 kg ha⁻¹ y⁻¹ which was much higher than in wheat. These declined yields were mostly linked to both gradual dry weather and nutrients depletion of the soil. The N only resulted in both P and K deficiency in the soil, and soil N and K negative balances in the NP and MNP were obvious. Soil organic carbon (SOC) in the 0-20 cm soil layer increased with time except in the CK and N treatments, in which SOC remained almost stable. In the MNP and M treatments, 24.7% and 24.0% of the amount of cumulative C input from organic sources remained in the soil as SOC, but 13.7% of the C input from straw and root in the SNP, suggesting manure is more effective in building soil C than straw. Across the 26 y cropping and fertilization, annual soil-C sequestration rates ranged from 0.014 t C ha⁻¹ y⁻¹ for the CK to 0.372 t C ha⁻¹ y⁻¹ for the MNP. We found a strong linear relationship (R² = 0.74, p = 0.025) between SOC sequestration and cumulative C input, with C conversion-to-SOC rate of 16.9%, suggesting these dryland soils have not reached an upper limit of C sequestration.
The photocatalytic CO2 reduction reaction (CRR) represents a promising route for the clean utilization of stranded renewable resources, but poor selectivity resulting from the competing hydrogen ...evolution reaction (HER) in aqueous solution limits its practical applicability. In the present contribution a photocatalyst with hydrophobic surfaces was fabricated. It facilitates an efficient three‐phase contact of CO2 (gas), H2O (liquid), and catalyst (solid). Thus, concentrated CO2 molecules in the gas phase contact the catalyst surface directly, and can overcome the mass‐transfer limitations of CO2, inhibit the HER because of lowering proton contacts, and overall enhance the CRR. Even when loaded with platinum nanoparticles, one of the most efficient HER promotion cocatalysts, the three‐phase photocatalyst maintains a selectivity of 87.9 %. Overall, three‐phase photocatalysis provides a general and reliable method to enhance the competitiveness of the CRR.
Die photokatalytische CO2‐Reduktion (CRR) in wässriger Lösung ist eine vielversprechende Reaktionroute, starke H2‐Erzeugung (HER) schränkt allerdings die Selektivität und Aktivität stark ein. Eine Strategie wurde entwickelt, um einen dreiphasigen Kontakt von CO2 (Gas), H2O (Flüssigkeit) und Katalysator (Feststoff) herzustellen und so die Stofftransferlimitierung von CO2 zu überwinden, die CO2‐Konzentration auf der Katalysatoroberfläche zu erhöhen, HER zu unterdrücken und die Aktivität und Selektivität der CRR zu erhöhen.
Photocatalytic CO2 reduction represents a sustainable route to generate syngas (the mixture of CO and H2), which is a key feedstock to produce liquid fuels in industry. Yet this reaction typically ...suffers from two limitations: unsuitable CO/H2 ratio and serious charge recombination. This paper describes the production of syngas from photocatalytic CO2 reduction with a tunable CO/H2 ratio via adjustment of the components and surface structure of CuPt alloys and construction of a TiO2 mesoporous hollow sphere with spatially separated cocatalysts to promote charge separation. Unlike previously reported cocatalyst-separated hollow structures, we firstly create a reductive outer surface that is suitable for the CO2 reduction reaction. A high evolution rate of 84.2 μmol h−1 g−1 for CO and a desirable CO/H2 ratio of 1 : 2 are achieved. The overall solar energy conversion yield is 0.108%, which is higher than those of traditional oxide and sulfide based catalysts (generally about 0.006–0.042%). Finally, density functional theory calculations and kinetic experiments by replacing H2O with D2O reveal that the enhanced activity is mainly determined by the reduction energy of CO* and can be affected by the stability of COOH*.
Electroreduction of carbon monoxide (CO) possesses great potential for achieving the renewable synthesis of hydrocarbon chemicals from CO2. We report here selective reduction of CO to acetate using ...Cu–Pd bimetallic electrocatalysts. High activity and selectivity are demonstrated for CO-to-acetate conversion with >200 mA/cm2 in geometric current density and >65% in Faradaic efficiency (FE). An asymmetrical C–C coupling mechanism is proposed to explain the composition-dependent catalytic performance and high selectivity toward acetate. This mechanism is supported by the computationally predicted shift of the *CO adsorption from the top-site configuration on Cu (or Cu-rich) surfaces to the bridge sites of Cu–Pd bimetallic surfaces, which is also associated with the reduction of the CO hydrogenation barrier. Further kinetic analysis of the reaction order with respect to CO and Tafel slope supports a reaction pathway with *CO–*CHO recombination following a CO hydrogenation step, which could account for the electroreduction of CO to acetate on the Cu–Pd bimetallic catalysts. Our work highlights how heteroatomic alloy surfaces can be tailored to enable distinct reaction pathways and achieve advanced catalytic performance beyond monometallic catalysts.
Electrochemical reduction of nitrate to ammonia (NH3) converts an environmental pollutant to a critical nutrient. However, current electrochemical nitrate reduction operations based on monometallic ...and bimetallic catalysts are limited in NH3 selectivity and catalyst stability, especially in acidic environments. Meanwhile, catalysts with dispersed active sites generally exhibit a higher atomic utilization and distinct activity. Herein, we report a multielement alloy nanoparticle catalyst with dispersed Ru (Ru-MEA) with other synergistic components (Cu, Pd, Pt). Density functional theory elucidated the synergy effect of Ru-MEA than Ru, where a better reactivity (NH3 partial current density of −50.8 mA cm–2) and high NH3 faradaic efficiency (93.5%) is achieved in industrially relevant acidic wastewater. In addition, the Ru-MEA catalyst showed good stability (e.g., 19.0% decay in FENH3 in three hours). This work provides a potential systematic and efficient catalyst discovery process that integrates a data-guided catalyst design and novel catalyst synthesis for a range of applications.
The facile synthesis of electrophoretic particles for electrophoretic displays (EPDs) with fast response and precise image control is a challenge. In this work, monodisperse silica nanoparticles were ...prepared by a sol-gel process in reverse microemulsion combined with solvent-thermal treatment, and modified with ionic liquid. The silica nanoparticles before and after surface modification are all monodisperse and smooth spheres. They also own suitable densities and excellent chromaticity for EPDs. The structure of ionic liquid modifiers shows remarkably influence on surface property and electrophoretic property of modified silica nanoparticles. The modified silica nanoparticles show improved hydrophobicity favoring for dispersion stability and suspension stability in the dispersant. The surface charge performance of modified silica nanoparticles are depending on competitive cooperation between ion pairs and alkyl groups of ionic liquids, and can be adjusted through tuning ionic liquid structure. The fabricated EPD prototypes show response time of 180–191 ms in the electrophoretic display cell with 0.2 mm thickness, much faster than the commercial EPDs.
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•Silica nanoparticles were prepared and modified with ionic liquid.•The obtained nanoparticles are all porous, monodisperse and smooth spheres.•The obtained nanoparticles own low density and excellent chromaticity for EPDs.•Ionic liquid affect remarkably surface property and charge performance of silica.•ARImBr/SiO2 show excellent electrophoretic mobility and fast response property.
Some typical dual-ring erbium-doped fiber lasers with hyperchaos behaviors are taken as nodes to construct two kinds of small-world networks—NW and WS networks. Based on Lyapunov stability theorem, ...the appropriate controllers are designed and the outer synchronization between the small-world networks with diverse structures and different node numbers is further investigated. The simulation results show that the perfect synchronization between the complex small-world networks is realized, which is of potential application for all optical communication network.
•Hyperchaotic Er-doped fiber lasers are adopted to construct complex networks.•Node number of NW small-world network is different from that of WS network.•Controllers are designed and outer synchronization is realized between networks.•Simulations prove controller design in our work is reasonable and effective.
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