CO Yield Research Articles

Engineering Single Ni Sites on 3D Cage‐like Cucurbit[n]uril Ligands for Efficient and Selective CO2 Photocatalytic Reduction

AbstractSolar‐driven CO2 selective reduction with high conversion is a challenging task yet holds immense promise for both CO2 neutralization and green fuel production. Enhancing CO2 adsorption at the catalytic centre can trigger a highly efficient CO2 capture‐to‐conversion process. Herein, we introduce cucurbit[n]urils (CB[n]), a new family of molecular ligands, as a key component in the creation of a 3D cage‐like metal (nickel, Ni)‐complex molecular co‐catalyst (CB[7]‐Ni) for photocatalysis. It exhibits an unprecedented CO yield rate of 72.1 μmol ⋅ h−1 with a high selectivity of 97.9 % under visible light irradiation. To verify the origin of the carbon source in the products, a straightforward isotopic tracing method is designed based on tandem reactions. The catalytic process commences with photoelectron transfer from Ru(bpy)32+ to the Ni2+ site, resulting in the reduction of Ni2+ to Ni+. The locally enriched CO2 molecules in the cage ligand CB[7] undergo selective reduction by the Ni+ nearby to form CO product. This work exemplifies the inspiring potential of ligand structure engineering in advancing the development of efficient unanchored molecular co‐catalysts.

Enabling Interfacial Lattice Matching by Selective Epitaxial Growth of CuS Crystals on Bi2WO6 Nanosheets for Efficient CO2 Photoreduction into Solar Fuels

AbstractPhotocatalytic CO2 reduction serves as an important technology for value‐added solar fuel production, however, it is generally limited by interfacial charge transport. To address this limitation, a two‐dimensional/two‐dimensional (2D/2D) p‐n heterojunction CuS‐Bi2WO6 (CS‐BWO) with highly connected and matched interfacial lattices was designed in this work via a two‐step hydrothermal tandem synthesis strategy. The integration of CuS with BWO created a robust interface electric field and provided fast charge transfer channels due to the work function difference, as well as highly connected and matched interfacial lattices. The p‐n heterojunction combination promoted the electron transfer from the Cu to Bi sites, leading to the coordination of Bi sites with high electronic density and low oxidation state. The Bi sites in the BWO nanosheets facilitated the adsorption and activation of CO2, and the generation of high‐coverage key intermediate b‐CO32−, while CuS (CS) acted as a broad light‐harvesting material to provide abundant photoinduced electrons that were injected into the conduction band of BWO for CO2 photoreduction reaction. Remarkably, the p‐n heterojunction CS‐BWO exhibited average CO and CH4 yields of 33.9 and 16.4 μmol g−1 h−1, respectively, which were significantly higher than those of CS, BWO, and physical mixture CS‐BWO samples. This work provided an innovative design strategy for developing high‐activity heterojunction photocatalyst for converting CO2 into value‐added solar fuels.

Novel Inorganic‐Organic Dual‐Photosensitizing Dinuclear‐Metal Self‐Assembly System for Efficient Artificial Photosynthesis without Sacrificial Electron Donors

AbstractOwing to the unique synergistic effect, dinuclear‐metal‐molecule‐catalysts (DMCs) show excellent performance in catalytic fields. However, for overall photocatalytic CO2 reaction (CO2RR), it is still a challenge to construct well‐matched photosensitizer (PS) components for DMCs‐based photocatalysts. Inorganic‐quantum‐dot PS possesses capacities of multiple exciton generation and catalyzing water oxidation but is incompatible with DMCs. In contrast, organic PS can be covalently linked with DMCs but inescapable of using sacrificial electron donors. For overall photocatalytic CO2RR, organic–inorganic dual‐photosensitizing system might be a promising candidate. Herein, we employed covalent‐linking and electrostatic‐driven approaches to construct the self‐assembly of pyrene‐sensitized Co2L DMCs (Py‐Co2L) and perovskite (PVK) quantum dots, i.e., PVK@[Py‐Co2L]. Using H2O as an electron donor, PVK@[Py‐Co2L] realized 105.24 μmol ⋅ g−1⋅h−1 CO yield in photocatalytic CO2RR, much higher than PVK (15.44 μmol ⋅ g−1⋅h−1) and PVK@Co2L (32.30 μmol ⋅ g−1 ⋅ h−1), ascribing to the efficient photogenerated charge separation and transfer. The experimental results and theoretical investigations demonstrated that the pyrene linked on Co2L boosted the electron delivery from PVK to DMCs. Besides, this strategy could also be extended to the photocatalytic H2 evolution coupled with alcohol oxidation. As a proof‐of‐concept, our work lightens the integration of DMCs, organic and inorganic PS components, promoting the development of photocatalysis without sacrificial electron donors.

Co‐feeding CO2 for Methylfuran Aromatization over Bifunctional Zeolite‐supported ZnMoO4

Aromatization of biofuran offers promising approaches for sustainable biochemical production. However, this process is often hampered by low yields and severe coking on traditional zeolite catalysts. Herein, we report co‐feeding CO2 for 2‐methylfuran (MF) aromatization (CCMA) over bifunctional ZSM‐5 supported ZnMoO4. This bifunctional catalyst can achieve both MF and CO2 conversions of >97%, generating >85% carbon yield of target arenes and CO with negligible alkenes (0.05%). Meanwhile, coke formation is remarkably suppressed from 22.3% to 8.6%. ZnMoO4/ZSM‐5 is capable of selectively manipulating the reaction intermediates and pathways of the CCMA reactions, favoring the cyclopentenones‐ and alkenes‐based dehydro‐aromatization rather than the benzofurans‐based pathway. This finding challenges the prevailing understanding that MF aromatization follows a hydrocarbon pool mechanism. Moreover, the abundant surface oxygen vacancies of ZnMoO4 facilitate the adsorption of CO2 and its subsequent reaction with coke. These insights into reaction mechanism and catalyst design for co‐conversion of CO2 and biofuran can offer guidelines for process intensification in biomass utilization with a carbon‐negative manner.

Co-feeding CO2 for Methylfuran Aromatization over Bifunctional Zeolite-supported ZnMoO4.

Aromatization of biofuran offers promising approaches for sustainable biochemical production. However, this process is often hampered by low yields and severe coking on traditional zeolite catalysts. Herein, we reportco-feeding CO2 for 2-methylfuran (MF) aromatization (CCMA) over bifunctional ZSM-5 supported ZnMoO4. This bifunctional catalyst can achieve both MF and CO2 conversions of >97%, generating >85% carbon yield of target arenes and CO with negligible alkenes (0.05%). Meanwhile, coke formation is remarkably suppressed from 22.3% to 8.6%. ZnMoO4/ZSM-5 is capable of selectively manipulating the reaction intermediates and pathways of the CCMA reactions, favoring the cyclopentenones- and alkenes-based dehydro-aromatization rather than the benzofurans-based pathway. This finding challenges the prevailing understanding that MF aromatization follows a hydrocarbon pool mechanism. Moreover, the abundant surface oxygen vacancies of ZnMoO4 facilitate the adsorption of CO2 and its subsequent reaction with coke. These insights into reaction mechanism and catalyst design for co-conversion of CO2 and biofuran can offer guidelines for process intensification in biomass utilization with a carbon-negative manner.

Efficient UV-Vis-NIR Responsive CO2 Reduction Photocatalyst with Black Pinecone-Shaped Carbon Nitride Loaded with Lanthanum Oxide.

Photothermal catalysis combines the advantages of photocatalysis and thermal activation, which provides a new research angle for CO2 catalytic reduction. In this study, Black carbon nitride with a three-dimensional (3D) pinecone-shaped structure (BPCN) was prepared by a simple solvothermal method using melamine as a precursor without the aid of a template. Lanthanum oxide doping on the BPCN catalysts (BPCN-La) was achieved by ultrasonic impregnation. This unique pinecone-shaped structure consists of self-assembled and interlaced carbon nitride rods (by SEM). The lanthanum element was distributed on the surface of the CN framework in the form of La2O3 (by XPS). The chemical structures of the samples were characterized by solid-state 13C nuclear magnetic resonance (13C NMR) and elaborated by density functional theory (DFT) analysis. This black carbon nitride expanded the light absorption band edge into the near-infrared (NIR) (300-1400 nm, by UV-vis absorption spectra) and had excellent photothermal conversion activity. La atom doping can significantly boost photogenerated electron excitation (by photocurrent test) and promote carrier separation and transfer (by PL). Upon incorporation of La atoms into BPCN, the highest occupied molecular orbital (HOMO) orbital is more concentrated on the oxygen atoms of La2O3. BPCN-La considerably narrowed the band gap width, exhibited an exceptional photothermal effect, and provided a large surface area, which significantly enhanced the photocatalytic reduction of CO2 reactions. The yields of CO reached 58.2 and 104.9 μmol·h-1·g-1 for BPCN and BPCN-La, respectively, with GCN as the control (6.3 μmol·h-1·g-1). Theoretical reaction pathways and selectivity for the photoreduction of CO2 on BPCN and BPCN-La were studied by DFT simulation. This work provides a new vision for the design of photothermal synergistic without extra-thermal input and full spectral response photocatalysts with high efficiency.

Amyloid-Like Protein-Modified Carbon Nitride as a Bioinspired Material for Enhanced Photocatalytic CO2 Reduction.

Modification of g-C3N4 with metal-free biomaterials through an environmentally friendly, low-energy, facile, and rapid single-step method is desired for the preparation of photocatalysts with efficient activity and high selectivity of CO2 reduction but remains a great challenge. Herein, we develop a phase-transitioned protein modification strategy for photocatalysts through superfast amyloid-like protein assembly on surfaces using a one-step sequential coating method. Metal-free carbon nitride/protein heterojunction composite photocatalysts (the phase-transitioned lysozyme (PTL), phase-transitioned bovine serum albumin (PTB), and phase-transitioned ovalbumin (PTO)-coated carbon nitride@SiO2 (CN@SiO2) and bioinspired carbon nitride hollow nanospheres (CN-HS) obtained by etching of CN@SiO2) are prepared using lysozyme, bovine serum albumin, and ovalbumin. The insulator-semiconductor heterojunctions formed at the protein-carbon nitride interface promote the migration and separation of photogenerated charges. The exposed hydrophobic alkyl and aryl groups of the surface-modified protein enable the formation of a CO2-aqueous solution-photocatalyst three-phase interface on the catalyst surface and the exposed -NH2 groups provide sites for CO2 adsorption, which effectively increases CO2 mass transfer and its adsorption as well as hydrophobicity, promoting CO2 reduction and inhibiting hydrogen production. Therefore, protein modification effectively improves the CO2 reduction activity and CO selectivity. For instance, compared to CN-HS, the CO yield of the PTL-modified CN-HS (1346.5 μmol g-1) increased by 24.5 times and the CO selectivity reached 90.5%. These findings represent a critical advancement in the surface modification of carbon nitride for CO2 reduction and the design of bioinspired materials for various applications.

Polyoxometalates‐Mediated Selectivity in Pt Single‐Atoms on Ceria for Environmental Catalysis

AbstractOptimizing the reactivity and selectivity of single‐atom catalysts (SACs) remains a crucial yet challenging issue in heterogeneous catalysis. This study demonstrates selective catalysis facilitated by a polyoxometalates‐mediated electronic interaction (PMEI) in a Pt single‐atom catalyst supported on CeO2 modified with Keggin‐type phosphotungstate acid (HPW), labeled as Pt1/CeO2‐HPW. The PMEI effect originates from the unique arrangement of isolated Pt atoms and HPW clusters on the CeO2 support. Electrons are transferred from the ceria support to the electrophilic tungsten in HPW clusters, and subsequently, Pt atoms donate electrons to the now electron‐deficient ceria. This phenomenon enhances the positive charge of Pt atoms, moderating O2 activation and limiting lattice oxygen mobility compared to the conventional Pt1/CeO2 catalyst. The resulting electronic structure of Pt combined with the strong and local acidic environment of HPW on Pt1/CeO2‐HPW leads to improved efficiency and N2 selectivity in the degradation of NH3 and NO, as well as increased CO2 yield when inputting volatile organic compounds. This study sheds the light on the design of SACs with balanced reactivity and selectivity for environmental catalysis.

The indirect global warming potential of methane oxidation in the IPCC’s sixth assessment report

Abstract Greenhouse-gas emission (GHG) metric values for methane in the sixth assessment report by the Intergovernmental Panel on Climate Change (IPCC) include the indirect effect associated to the oxidation of methane to CO2. An analysis of the figures provided by the IPCC reveals they assume that in average 75% of methane is ultimately oxidized to CO2, while the remaining 25% is converted to intermediate degradation products, most notably formaldehyde, which are removed from the atmosphere via wet and dry deposition and treated by the IPCC as a potential carbon sink in terrestrial and aquatic ecosystems. In this short article we present a critique to this assumption, based on existing knowledge about the environmental fate of methane’s degradation products. We conclude that any assumption other than full degradation of methane to CO2 in a rather short time frame is questionable, whereby the default CO2 yield from this oxidation, as far as GHG metrics are concerned, should be 100%. We re-calculate values for the global warming potential (GWP) metric in accordance with our findings, resulting in an increase in GWP100 from 29.8 and 27.0 to 30.40 and 27.65 kg CO2-equivalents/kg fossil and biogenic methane, respectively. Although we only present the implications in terms GWP, our proposal is conceptually valid for other GHG metrics as well.

Hydrogen production and elemental migration during supercritical water gasification of food waste digestate

The rapid growth of food waste (FW) is a huge challenge on a global scale, and anaerobic digestion is one of the most commonly used methods to deal with food waste, and the increasing amount of food waste digestate (FWD) produced by anaerobic digestion also poses a huge challenge to waste management. This paper explores supercritical water gasification (SCWG) as a valuable and innovative strategy for the conversion of FWD into H2-rich syngas. The research focuses on analyzing the effects of reaction temperature and residence time on syngas production, gas composition, element migration (C, N and P) during the SCWG process. Experimental results show that as the reaction temperature increases from 400 °C to 500 °C, the total syngas yield increases significantly, from 2.4 mol/kg to 9.7 mol/kg, especially the yields of H2, CO2, and CH4. As the reaction temperature increases and the residence time increases, the migration of carbon from the solid and liquid phases to the gas phase accelerates with increasing temperature and residence time, resulting in a higher proportion of carbon in the gas phase. In terms of liquid phase composition, nitrogenous compounds are significantly converted into ammonium (NH4+-N) at higher temperatures. In addition, the organic phosphorus is observed transferring into inorganic phosphorus, which are mainly apatite. This study explores the scalability of SCWG and its potential for the production of clean fuels, thereby contributing to the sustainable management of FWD.

In-situ preparation of BiOBr/Bi-doped CsPbBr3 S-scheme heterojunction for efficient photocatalytic CO2 reduction

Metal halide perovskite nanocrystals have garnered significant attention in the realm of photocatalytic CO2 reduction in recent years owing to their remarkable reducing properties and high selectivity. However, the issue of low photocatalytic activity due to severe carrier recombination phenomena in perovskite has posed a significant challenge. To address this, a one-pot in-situ preparation strategy was employed to create a BiOBr/Bi-doped perovskite nanocrystal S-scheme heterojunction, resulting in a significant improvement in the CO2 photoreduction performance. The heterojunction material exhibited a CO yield of 151.56 μmolg-1h−1, with a selectivity for CO of 93.6 %. The molar ratio of the components was modulated using an in-situ water aging strategy, yielding a photocatalyst performance that exceeded that of pure BiOBr. The synthesis strategy of one-step in-situ preparation of heterojunctions overcomes the problem of insufficient bonding caused by two-step methods. And various characterizations and DFT calculations strongly support the S-scheme mechanism of the photocatalyst. The active site effectively reduces the energy barrier for the transition from *COOH to *CO intermediate, thereby significantly improving photocatalytic activity.

Pivotal copper bimetallic oxide in hierarchical Calcium magnesium materials for low-temperature carbon capture and utilization

Carbon removal from anthropogenic greenhouse gas emissions is essential to achieve net-zero emissions and mitigate climate change, and integrated carbon capture and utilisation (ICCU) has been studied for subsequent in-situ chemical production. However, high temperature and CaO sintering remain critical issues, highlighting the need for improved, low-cost CO2 adsorbents that can be regenerated at lower temperatures. Herin, we innovatively introduce the low-temperature ICCU coupled with reverse water gas shift reactions (RWGS) using dual functional materials (DFMs), exemplifying a range of potential transition metals doped over CaO with or without the MgO support. Among all the prepared DFMs, D-Cu showed desirable enhanced catalytic activity at a comparatively low-temperature performance (550°C) and still maintained a stable CO2 capture capacity (7.0mmol g−1) and CO yield (8.0mmol g−1) with an exceptional CO2 conversion (94.4 %) and CO selectivity (97.6 %) after cyclic hydrogenation. The mechanism study revealed that Ca2CuO3 bimetalliccatalyst in the hierarchical porous 2CaO/MgO matrix of D-Cu plays a crucial role in retaining its cyclic stability, surpassing that of noble D-Pt. Given the ICCU-RWGS performance and cyclic stability of cost-effective D-Cu at reduced operating temperatures, the findings would minimise energy and cost consumption.

Hydroxide-ion induced complete mineralization of poly(tetrafluoroethylene-co-hexafluoropropylene) copolymer (FEP) in subcritical water

Decomposition of poly(tetrafluoroethylene-co-hexafluoropropylene) copolymer (FEP) in supercritical and subcritical water was investigated with the aim of waste treatment. The efficiency of such decomposition was examined by using either oxidizing agents (O2, H2O2) or an alkaline reagent (KOH). When O2 was chosen, the highest F– and CO2 yields, 75 % and 64 %, respectively, were obtained from a reaction of FEP in supercritical water at 384 °C for 24 h. Under these conditions, traces of CHF3 were detected in the gas phase, the amount of which decreased with increasing the reaction time·H2O2 gave slightly higher reactivity than O2. In contrast, reactions with KOH induced efficient fluorine mineralization. When FEP reacted in 3.0 M KOH solution at 360 °C for 18 h, the F– yield reached 98 %. Hence, complete fluorine mineralization was achieved, where very little CO2 (∼0% yield) and no CHF3 were generated in the gas phase. Furthermore,19F NMR spectroscopy and combustion-ion chromatography revealed that the reaction solutions did not contain any organofluorine compounds during the reactions. FEP decomposed, releasing F– into the reaction solution, resulting in the formation of amorphous carbon in the residue.

Hydroxylated SiO2-modified {0 0 1}-TiO2 nanosheets as a surface multifunctional photocatalyst for enhanced degradation of gaseous toluene

The relatively weak activity and serious deactivation of anatase TiO2 nanosheet catalysts with highly exposed {001} facets ({001}-TiO2) limits its wide application in photocatalytic degradation of gaseous pollutants. Herein, we propose a hybrid photocatalyst composed of {001}-TiO2 and SiO2 with numerous hydroxyl groups (denoted as {001}-TiO2/HO-SiO2). The catalyst showed excellent performance for gaseous toluene degradation under UV illumination, with 99.2 % removal efficiency and 204.7 μmol L−1 CO2 yield (about 85.9 % mineralization efficiency) within 120 min. It also demonstrated superior durability over five consecutive cycles of toluene photodegradation. The modification of HO–SiO2 on {001}-TiO2 facilitate the selective adsorption of toluene on the catalyst surface by H-bonding interaction, and make the major poisoning species, benzoic acid, easily desorb from the surface, reducing the catalyst inactivation. Most importantly, we found that the formed TiOSi bond promotes the separation of photogenerated electron–hole pairs, and provides abundant available electrons for the formation of reactive oxygen radicals and the left holes for the conversion of toluene to benzyl radicals or oxidation of H2O to hydroxyl radicals, which results in the improved activity. This study highlights the importance of the introduction of secondary components with special functions on TiO2, which is helpful for the design of photocatalysts with high performance and anti-deactivation ability for treatment of volatile organic compounds.

Structure dependence of the enhanced sulfur tolerance of core–shell CoMn oxides for benzene oxidation: Discrepant sulfur species and less affected reactant activation

Effective reduction of VOCs emissions in practical gas requires low-temperature catalysts with remarkable SO2 tolerance. Here via simply mixing CoCO3 into the precursors of α-MnO2, a core–shell CoMn composite was developed. The leading one with CoCO3 addition of 3 g (Co3Mn) achieved 100 % C6H6-to-CO2 conversion at ≥250 °C under 120 L/g/h, and still the CO2 yield over the sulfurized Co3Mn (simulated by H2SO3 vapor pretreatment) was maintained 100 %. However, with respect to the case of fresh MnO2, the CO2 production at 250 and 300 °C over the sulfurized MnO2 was decreased by 26 % and 8 %, respectively, and in the meantime, a larger amount of CO was detected. The dominant formation of abundant MnSO4 species due to sulfur poisoning led to the deactivation of pure MnO2, while over Co3Mn the formation of MnSO4 was significantly inhibited because of (i) the electron transfer from Co2+ to Mn4+ restraining that from S4+ to Mn4+ and (ii) the stronger alkalinity of Co species making the acidic H2SO3 preferentially anchor on Co as CoSO4. Along with the sacrificial role, another way cobalt alleviated sulfate toxicity was through transiting the aggregated sulfate deposition into scattered state. Investigations conducted primarily with UV–vis DRS and temperature-programmed techniques further reveal that neither MnO2 nor Co3Mn could escape from the sulfur-induced adversity on activation of O2 and benzene, but the sulfurized Co3Mn was much less affected, thus sustaining the deep benzene oxidation. Finally, reaction routes were unraveled according to the phenol, benzoquinone, maleic acid and acetic acid intermediates.

Engineering Single Ni Sites on 3D Cage-like Cucurbit[n]uril Ligands for Efficient and Selective CO2 Photocatalytic Reduction.

Solar-driven CO2 selective reduction with high conversion is a challenging task yet holds immense promise for both CO2 neutralization and green fuel production. Enhancing CO2 adsorption at the catalytic centre can trigger a highly efficient CO2 capture-to-conversion process. Herein, we introduce cucurbit[n]urils (CB[n]), a new family of molecular ligands, as a key component in the creation of a 3D cage-like metal (nickel, Ni)-complex molecular co-catalyst (CB[7]-Ni) for photocatalysis. It exhibits an unprecedented CO yield rate of 72.1 µmol· h-1 with a high selectivity of 97.9% under visible light irradiation. To verify the origin of the carbon source in the products, a straightforward isotopic tracing method is designed based on tandem reactions. The catalytic process commences with photoelectron transfer from Ru(bpy)32+ to the Ni2+ site, resulting in the reduction of Ni2+ to Ni+. The locally enriched CO2 molecules in the cage ligand CB[7] undergo selective reduction by the Ni+ nearby to form CO product. This work exemplifies the inspiring potential of ligand structure engineering in advancing the development of efficient unanchored molecular co-catalysts.

Enabling Interfacial Lattice Matching by Selective Epitaxial Growth of CuS Crystals on Bi2WO6 Nanosheets for Efficient CO2 Photoreduction into Solar Fuels.

Photocatalytic CO2 reduction serves as an important technology for value-added solar fuel production; however, it is generally limited by interfacial charge transport. To address this limitation, a two-dimensional/two-dimensional (2D/2D) p-n heterojunction CuS-Bi2WO6 (CS-BWO) with highly connected and matched interfacial lattices was designed via a two-step hydrothermal tandem synthesis strategy. The integration of CuS with BWO created a robust interface electric field and provided fast charge transfer channels due to the work function difference, as well as highly connected and matched interfacial lattices. The p-n heterojunctionpromotedelectron transfer from the Cu to Bi sites, leading to coordination of Bi sites with high electronic density and low oxidation state. The Bi sites in BWO nanosheets facilitated the adsorption and activation of CO2, and generation of high-coverage key intermediate b-CO32-, while broad light-harvesting CuS (CS)provide abundant photoinduced electrons that were injected into the conduction band of BWO for CO2 photoreduction reaction. Remarkably, the p-n heterojunction CS-BWO exhibited CO and CH4 yields of 135.7 and 62.5 µmol g-1, respectively, which were significantly higher than those of CS, BWO, and physical mixture CS-BWO nanosheets. This work provided an innovative design strategy for developing high-activity heterojunction photocatalyst for converting CO2into value-added solar fuels.

Research on reaction mechanisms on chemical looping gasification of naphthalene over NiFe2O4 for syngas production: An experimental and theoretical study

The effective removal of tar during biomass gasification is a significant challenge that can be addressed by chemical looping gasification (CLG), which offers a promising alternative for converting biomass into syngas with reduced tar generation. In this study, we investigated the mechanism of CLG of naphthalene as a model biomass tar compound over NiFe2O4 to produce syngas. Both experimental and simulation results indicate the optimal operating conditions for syngas production are 1000℃ and an O/C ratio of 1:1. Under the optimal reaction conditions, the experimental and simulated CO yields were 67 vol% and 73 vol%, respectively, while H2 yields were 22 vol% and 24 vol%. Additionally, carbon conversion rates reached 78% and 76%. Thermodynamic calculations and molecular dynamics simulations revealed that the reactions proceed spontaneously, with increasing temperature favoring naphthalene conversion and syngas production. Density functional theory results indicate that the reaction pathway centered on the carbon at the α-position is the key to naphthalene and NiFe2O4 conversion. The optimal reaction pathways for H2 and CO formation were explored. This study on the CLG of naphthalene over NiFe2O4 provides a theoretical basis for the development of more efficient CLG processes with reduced tar formation.

Insights into the influence of anions on the syngas production behavior of bio-wastes during molten salt thermal treatment

Thermal treatment of bio-wastes in molten nitrate at low temperatures has emerged as an efficient approach for producing syngas. Molten salt facilitates the thermal conversion of bio-wastes due to its superior heat transfer and catalytic properties. To enhance the depolymerisation of macromolecules in bio-wastes for the production of high-quality syngas, molten NaNO3-NaNO2 with varying anion ratios was employed in this study, and the effects of these anions on bio-wastes with diverse properties were thoroughly investigated. The results indicated that NO3− tended to be significantly involved in the cleavage of carbonyl groups and C–C/CC bonds, which dominated the high CO2 production. NO2− tended to be significantly involved in the cleavage of ether and C–C/CC bonds, which dominated the high CO production. The elevated NO2− ratio in molten salt significantly facilitated the depolymerisation of bio-wastes, increasing the yield of combustible gases (CO, CH4, H2) while decreasing CO2 yield in the syngas. This resulted in a notable enhancement of the lower heating value (LHV) of syngas, reaching up to 11.55 MJ/Nm3. This behavior also led to the formation of substantial quantities of nitro-phenols and amines containing nitro/nitroso groups in the tar. The nitrosation reaction of NO2− with bio-wastes was the primary factor in this process and took precedence over the nitrification of NO3−. This study elucidated the reaction pathways of NO3−/NO2− with bio-wastes and their contributions to the production of high-quality syngas at low temperature.

Novel Inorganic-Organic Dual-Photosensitizing Dinuclear-Metal Self-Assembly System for Efficient Artificial Photosynthesis without Sacrificial Electron Donors.

Owing to the unique synergistic effect, dinuclear-metal-molecule-catalysts (DMCs) show excellent performance in catalytic fields. However, for overall photocatalytic CO2 reaction (CO2RR), it is still a challenge to construct well-matched photosensitizer (PS) components for DMCs-based photocatalysts. Inorganic-quantum-dot PS possesses capacities of multiple exciton generation and catalyzing water oxidation but is incompatible with DMCs. In contrast, organic PS can be covalently linked with DMCs but inescapable of using sacrificial electron donors. For overall photocatalytic CO2RR, organic-inorganic dual-photosensitizing system might be a promising candidate. Herein, we employed covalent-linking and electrostatic-driven approaches to construct the self-assembly of pyrene-sensitized Co2L DMCs (Py-Co2L) and perovskite (PVK) quantum dots, i.e., PVK@[Py-Co2L]. Using H2O as an electron donor, PVK@[Py-Co2L] realized 105.24 μmol·g-1·h-1 CO yield in photocatalytic CO2RR, much higher than PVK (15.44 μmol·g-1·h-1) and PVK@Co2L (32.30 μmol·g-1·h-1), ascribing to the efficient photogenerated charge separation and transfer. The experimental results and theoretical investigations demonstrated that the pyrene linked on Co2L boosted the electron delivery from PVK to DMCs. Besides, this strategy could also be extended to the photocatalytic H2 evolution coupled with alcohol oxidation. As a proof-of-concept, our work lightens the integration of DMCs, organic and inorganic PS components, promoting the development of photocatalysis without sacrificial electron donors.