In Poland lignocellulose wastes constitute about 43% of municipal waste (∼4 417 Gg). Anaerobic and/or dark fermentation are sustainable methods of lignocellulosic waste-management and contribute ...greatly to ever increasing demand for energy and products. This paper presents the results of the theoretical potential of methane and hydrogen yields from lignocellulosic wastes. Also, state-of-the-art methods in the field of lignocellulose fermentation as well as its development and pretreatment are discussed. The main reason for applying pretreatment is the decomposition (decrystallization) of cellulose and hemicellulose and cleavage of polymers into monomers, which may be more easily digested by bacteria in DF and AD fermentation processes. At current price levels the cheapest methods are basic and acidic pretreatments. Acidic pretreatment is very efficient (especially using sulfuric acids), solubilizing up to 80% of lignocellulose, but strong acids produce inhibitors and are highly corrosive. Alkaline pretreatment is a competitive and even more efficient (>80%) method to acidic pretreatment especially for some rigid materials that acid cannot solubilize. Oxidative pretreatment is usually expensive but can support the sacharisation process by either alkaline or acidic methods; in the case of NMMO efficiency reaching 82%. Ion-liquid pretreatment is selective (almost 100% sacharisation) but very costly and is too expensive for hydrogen production. The last methods can be profitable if some valuable by-products results. An efficient chemical pretreatment should be preceded by physical comminution e.g. mechanical which is the cheapest one.
•Efficient anaerobic and/or dark fermentation of lignocellulose requires substrate pretreatment.•Acidic pretreatment -very popular and efficient but strong acids produce inhibitors and are strongly corrosive.•Designed pretreatment technique should prevent the corrosion stress.•Alkaline pretreatments are the cheapest (but polluting) while ionic and oxidants pretreatments are the most expensive.
Black phosphorus (BP), a star-shaped two-dimensional material, has attracted considerable attention owing to its unique chemical and physical properties. BP shows great potential in photocatalysis ...area because of its excellent optical properties; however, its applications in this field have been limited to date. Now, a Z-scheme heterojunction of 2D/2D BP/monolayer Bi
WO
(MBWO) is fabricated by a simple and effective method. The BP/MBWO heterojunction exhibits enhanced photocatalytic performance in photocatalytic water splitting to produce H
and NO removal to purify air; the highest H
evolution rate of BP/MBWO is 21042 μmol g
, is 9.15 times that of pristine MBWO and the NO removal ratio was as high as 67 %. A Z-scheme photocatalytic mechanism is proposed based on monitoring of
O
,
OH, NO
, and NO
species in the reaction. This work broadens applications of BP and highlights its promise in the treatment of environmental pollution and renewable energy issues.
•A novel noble metal-free ZnIn2S4/WC heterojunction was synthesized based on the combination of semiconductor and metal-like.•The optimal ZnIn2S4/WC photocatalysts have a lower overpotential for ...hydrogen evolution than pristine ZnIn2S4.•The H2 production ability of the optimal ZnIn2S4/WC was about 9.2 times than that of ZnIn2S4-1% Pt.•A feasible Schottky junction reaction mechanism of intensive photocatalytic activity was discussed.
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Herein, we report the synthesis of ZnIn2S4 nanoparticles on bulk WC by a facile hydrothermal process to construct novel and highly efficient noble metal-free Schottky junction heterojunction photocatalysts. Morphology characterization revealed that the ZnIn2S4 nanoparticles were deposited on the surface of the WC. Meanwhile, the combination of the ZnIn2S4 and the metal-like WC formed the Schottky energy barrier, which greatly promoted the migration and separation of photo-generated carriers. Especially, the optimal ZnIn2S4/WC photocatalysts have a lower overpotential for hydrogen evolution (−0.35 V) than pristine ZnIn2S4 (−0.49 V). The hydrogen production ability of the optimal ZnIn2S4/WC photocatalyst (2400.3 μmol·h−1·g−1) was approximately 9.2 times higher than that of ZnIn2S4-1% Pt (260.1 μmol·h−1·g−1). Photocatalytic experiments demonstrated that metal-like WC plays an important role in replacing precious metal to increase the active site of ZnIn2S4. Moreover, a feasible Schottky junction reaction mechanism of intensive photocatalytic activity was discussed. This study proves that it is a very fascinating strategy to combine the advantages of ZnIn2S4 and metal-like to construct Schottky heterojunction for photocatalytic hydrogen production.
This study explored the photocatalytic hydrogen evolution reaction (HER) using novel biohydrogel composites comprising chitosan, and a photocatalyst consisting in TiO2 P25 decorated with Au and/or Cu ...mono- and bimetallic nanoparticles (NPs) to boost its optical and catalytic properties. Low loads of Cu and Au (1 mol%) were incorporated onto TiO2 via a green photodeposition methodology. Characterization techniques confirmed the incorporation of decoration metals as well as improvements in the light absorption properties in the visible light interval (λ > 390 nm) and electron transfer capability of the semiconductors. Thereafter, Au and/or Cu NP-supported TiO2 were incorporated into chitosan-based physically crosslinked hydrogels revealing significant interactions between chitosan functional groups (hydroxyls, amines and amides) with the NPs to ensure its encapsulation. These materials were evaluated as photocatalysts for the HER using water and methanol mixtures under simulated sunlight and visible light irradiation. Sample CuAuTiO2/ChTPP exhibited a maximum hydrogen generation of 1790 μmol g−1 h−1 under simulated sunlight irradiation, almost 12-folds higher compared with TiO2/ChTPP. Also, the nanocomposites revealed a similar tendency under visible light with a maximum hydrogen production of 590 μmol g−1 h−1. These results agree with the efficiency of photoinduced charge separation revealed by transient photocurrent and EIS.
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The strategic incorporation of the neurotransmitter dopamine around a cobaloxime core resulted in excellent electrocatalytic (rate 8400 s−1) and photocatalytic H2 production under neutral aqueous ...conditions. The influence of the synthetic outer coordination sphere features continues even with a phenylene–diimino–dioxime motif-coordinated cobalt core.
The electrochemical oxidation of small molecules to generate value‐added products has gained enormous interest in recent years because of the advantages of benign operation conditions, high ...conversion efficiency and selectivity, the absence of external oxidizing agents, and eco‐friendliness. Coupling the electrochemical oxidation of small molecules to replace oxygen evolution reaction (OER) at the anode and the hydrogen evolution reaction (HER) at the cathode in an electrolyzer would simultaneously realize the generation of high‐value chemicals or pollutant degradation and the highly efficient production of hydrogen. This Minireview presents an introduction on small‐molecule choice and design strategies of electrocatalysts as well as recent breakthroughs achieved in the highly efficient production of hydrogen. Finally, challenges and future orientations are highlighted.
Thermodynamically more favorable oxidation reactions of small molecules are widely implemented to replace the oxygen evolution reaction (OER) to achieve the highly efficient production of hydrogen. This Minireview systematically surveys the current progress in electro‐oxidation reactions involving diverse molecules, different electrolytes, and novel mechanisms. The challenges and research directions of this area are highlighted.
As a member of the ternary sulfides, CdIn2S4 is a visible light responded catalyst with a band gap of 2.2–2.6 eV, which is suitable for solar spectrum. In this study, a simple two-step solvothermal ...method was used to construct Ni12P5/In(OH)3/CdIn2S4 composite catalysts with type-II and Z-scheme heterojunctions, and there was a synergy between the two heterojunctions. The Ni12P5/In(OH)3/CdIn2S4 composite catalyst formed a donor-mediator-acceptor system for photogenerated electrons, which greatly improved the separation efficiency of the photogenerated carriers. Moreover, the highest hydrogen production activity achieved by the Ni12P5/In(OH)3/CdIn2S4 composites was 5.75 mmol g−1 h−1, which was 21 times the original CdIn2S4.
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