C2 Products Research Articles

Snowflake relocated Cu2O electrocatalyst on an Ag backbone template for the production of liquid C2+ chemicals from CO2.

In this study, we performed the CO2 reduction reaction (CO2RR) using a structural composite catalyst of cuprous oxide (Cu2O) and silver (Ag) that was simultaneously electrodeposited. While the underneath Ag electrodeposits maintained their spiky backbone structures even after the CO2RR, the Cu2O deposits were reduced to Cu(111) and relocated on the backbone template. The structural changes in Cu2O to Cu increase the active area of the Cu-Ag interface, resulting in a remarkable production rate of 125.01 μmol h-1 of liquid C2+ chemicals via the stabilization of the C-C coupling of the key intermediate species of acetaldehyde. This study provides new insights into designing a bimetallic catalyst for producing sustainable C2+ products from CO2 without any selectivity towards the production of methane.

A106: Aerobic Exercise Modulates GPCR/cAMP/PKA Signaling Pathway and Complement-Microglia Axis to Prevent Synaptic Loss in APP/PS1 Mice

Purpose: Synaptic failure serves as a primary contributor to memory dysfunction in Alzheimer's disease (AD). Physical exercise has demonstrated the potential to thwart and delay degenerative alterations in memory functions linked to AD. Investigating the underlying mechanisms may unveil crucial insights into early pathological changes, offering breakthroughs for both understanding and treating AD. Methods: We utilized 3-month-old APP/PS1 mice and subjected them to a 12-week aerobic exercise intervention. The spatial learning and memory functions of the mice were assessed using the Morris water maze test, while Golgi staining was employed to determine dendritic spine density in each mouse group. To analyze the potential mechanisms mediating the effects of exercise intervention in the AD brain, we conducted RNA sequencing. Subsequently, pathway enrichment analysis, immunofluorescence, real-time quantitative PCR, and western blotting were employed to elucidate the impact of regular aerobic exercise on the GPCR/cAMP/PKA signaling pathway and complement-microglia axis. Results: Our findings reveal that a 12-week aerobic exercise intervention significantly enhanced spatial learning and memory function in APP/PS1 mice. Moreover, it led to a substantial increase in dendritic spine density and elevated expression of postsynaptic density protein 95 (PSD-95) in the cortex and hippocampus. Aerobic exercise demonstrated the ability to improve the expression of certain genes and enhance synaptic pathways in the brains of APP/PS1 mice. This suggests that aerobic exercise facilitates synaptic growth in APP/PS1 mice by modulating G protein-coupled receptors (GPCRs) and activating the cAMP signaling pathway, with significant alterations observed in the expressions of Hcar1 and Vipr2 genes. Furthermore, exercise intervention resulted in the significant down-regulation (P < 0.05 or P < 0.01) of cAMP, p-PKA/PKA, GluA1, and CaMKII protein expressions in the brain tissue of APP/PS1 mice, which were subsequently up-regulated after exercise (P < 0.01). Notably, regular aerobic exercise effectively suppressed the activation of IBA-1+ microglia cells (P < 0.01), reversed changes in M1 phenotype markers (Cd86 and iNOS) and M2 phenotype markers (Arg-1) of microglia cells (P < 0.05), reduced the production of promoters C1q and central factor C3 in the macrosomatic cascade (P < 0.05), and prevented the colocalization of microglia and PSD-95 (P < 0.01). Conclusion: In conclusion, our results indicate that physical exercise plays a pivotal role in fostering early synaptic growth and averting synaptic loss in Alzheimer's disease (AD). This effect may be attributed to the regulation of the G protein-coupled receptors (GPCRs)/cAMP/PKA signaling pathway and the suppression of complement-mediated microglial phagocytosis of synapses. This mechanistic insight underscores the inherent contribution of exercise to health promotion, offering potential avenues for synaptic-focused interventions in the early stages of AD treatment.

‘It's the Programmes, Stupid’

AbstractPublic Service Broadcasting (PSB) is an eco‐system where the whole is more than the sum of its parts. The BBC is the cornerstone, but ITV, C4, C5 and independent production companies also play a crucial part. The essence of PSB lies in the values which underpin the content, ranging from popular sport and light entertainment to more niche minority strands. The BBC licence fee generates considerable value for the British economy throughout the nations and regions of the UK. This is multiplied by the intellectual property framework for independent production companies. The system is now under threat from the financial squeeze on the BBC licence fee, failure to deliver ‘due prominence’ to commercial PSBs, new technology and changing patterns of consumption. It is essential that a broad range of programmes remain freely available to avoid the cultural, social and political divisions of a two‐tier system of national broadcasting.

Nanoconfined tandem three-phase photocatalysis for highly selective CO2 reduction to ethanol.

The conversion of CO2 and H2O into ethanol with high selectivity via photocatalysis is greatly desired for effective CO2 resource utilization. However, the sluggish and challenging C-C coupling hinders this goal, with the behavior of *CO holding the key. Here, a nanoconfined and tandem three-phase reaction system is established to simultaneously enhance the *CO concentration and interaction time, achieving an outstanding ethanol selectively of 94.15%. This system utilizes a tandem catalyst comprising an Ag core and a hydrophobic Cu2O shell. The hydrophobic Cu2O shell acts as a CO2 reservoir, effectively overcoming the CO2 mass-transfer limitation, while the Ag core facilitates the conversion of CO2 to CO. Subsequently, CO undergoes continuous reduction within the nanoconfined mesoporous channels of Cu2O. The synergy of enhanced mass transfer, nanoconfinement, and tandem reaction leads to elevated *CO concentrations and prolonged interaction time within the Cu2O shell, significantly reducing the energy barrier for *CO-*CO coupling compared to the formation of *CHO from *CO, as determined by density functional theory calculations. Consequently, C-C coupling preferentially occurs over *CHO formation, producing excellent ethanol selectivity. These findings provide valuable insights into the efficient production of C2+ compounds.

Theoretical study on electrocatalytic carbon dioxide reduction over copper with copper-based layered double hydroxides.

The conversion of CO2 into valuable fuels and multi-carbon chemical substances by electrical energy is an effective strategy to solve environmental problems by using renewable energy sources. In this work, the density functional theory (DFT) method is used to reveal the electrocatalytic mechanism of CO2 reduction reaction (CO2RR) over the surface of CuAl-Cl-layered double hydroxides (LDHs) with Cu monoatoms (Cu@CuAl-Cl-LDH), Cu2 diatoms (Cu2@CuAl-Cl-LDH), orthotetrahedral Cu4 clusters (Td-Cu4@CuAl-Cl-LDH) and planar Cu4 clusters (Pl-Cu4@CuAl-Cl-LDH). The active sites, density of states, adsorption energy, charge density difference and free energy are calculated. The results show that CO2RR over all the above five catalysts can generate C2 products. Pl-Cu4@CuAl-Cl-LDH tends to generate C2H5OH, while the remaining four structures all tend to produce C2H4. Cuδ+ favors CO2RR, and Td-Cu4@CuAl-Cl-LDH with a larger positively charged area at the active site has the better electrocatalytic performance among the calculated systems with a maximum step height of 0.78 eV. The selectivity of the products C2H4 and C2H5OH depends on the dehydration of the intermediate *C2H2O to *C2H3O or *CCH; if the dehydration produces *CCH intermediate, the final product is C2H4, and if no dehydration occurs, C2H5OH is produced. This work provides theoretical information and guidance for further rational design of efficient CO2RR catalysts for energy saving and emission reduction.

Efficient photoreduction of carbon dioxide to ethanol using diatomic nitrogen-doped black phosphorus.

Successful conversion of CO2 into C2 products requires the development of new catalysts that overcome the difficulties in efficient light harvesting and CO-CO coupling. Herein, density functional theory (DFT) is used to assess the photoreduction properties of nitrogen-doped black phosphorus. The geometric structure, redox potential, first step of hydrogenation activation, CO desorption, and CO-CO coupling are systematically calculated, based on which the diatomic nitrogen-doped black phosphorus (N2@BPV) stands out. The calculated results of the CO2RR pathway demonstrate that N2@BPV has excellent selectivity and high activity for CH3CH2OH production. The results of the time-dependent ab initio nonadiabatic molecular dynamics simulation show that the diatomic N active sites of N2@BPV facilitate charge separation and inhibit electron-hole recombination. In addition, the activation mechanism of CO2 is studied. The main reason for CO2 activation is attributed to the imbalance in electron transfer that destroys the symmetry of CO2. We expect that our study will offer some theoretical guidance in CO2 conversion.

Confined CO in a sandwich structure promotes C-C coupling in electrocatalytic CO2 reduction.

Microenvironment regulation near the catalyst surface plays a critical role in heterogeneous electrocatalytic reactions. The local concentration of reactants and intermediates significantly affects the reaction kinetics and product selectivity. Herein, we propose an innovative strategy of utilizing the spatial confinement effect in a sandwich-structured C/Cu/C assembly to regulate kinetic mass transport during the electrocatalytic CO2 reduction reaction. The sandwich C/Cu/C assembly catalyst was successfully prepared using a simple bidirectional freezing and freeze-drying method. The sandwich structure changes the free diffusion pathway of the CO intermediate within the sandwich interlayer and helps confine CO with locally increased CO concentration near the catalyst surface, which in turn promotes C-C coupling and thus improves the reaction activity and doubles the C2 product selectivity compared to its disordered mixture counterpart. This kinetics regulation in the sandwich structure may provide a new insight into the catalyst design and inspire the understanding of the structure-performance relationship in electrocatalysis.

Metal-free electrocatalytic upcycling of polyethylene terephthalate plastic to C2 products.

Polyethylene terephthalate (PET) is one of the most used polymers, but the non-degradable and persistent nature of PET waste in the environment is a global menace. Hence upcycling PET waste becomes indispensable. Herein, we introduce the first metal-free electrochemical-upcycling of PET into value-added chemicals and H2 fuel using an organo-electrocatalyst (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO). Electrolysis at pH 10 produces glycolate and oxalate exclusively while at pH 14, over-oxidation and subsequent C-C bond cleavage produce formate and carbonate as well. Tuning the rate and product selectivity via pH regulation with mechanistic insight displays a sustainable route to implement waste PET recycling.

Mechanistic insights into high-throughput screening of tandem catalysts for CO2 reduction to multi-carbon products.

In carbon dioxide electrochemical reduction (CO2ER), since isolated catalysts encounter challenges in meeting the demands of intricate processes for producing multi-carbon (C2+) products, tandem catalysis is emerging as a promising approach. Nevertheless, there remains an insufficient theoretical understanding of designing tandem catalysts. Herein, we utilized density functional theory (DFT) to screen 80 tandem catalysts for efficient CO2ER to C2 products systematically, which combines the advantages of nitrogen-doped carbon-supported transition metal single-atom catalysts (M-N-C) and copper clusters. Three crucial criteria were designed to select structures for generation and transfer of *CO and facilitate C-C coupling. The optimal Cu/RuN4-pl catalyst exhibited an excellent ethanol production capacity. Additionally, the relationship between CO adsorption strength and transfer energy barrier was established, and the influence of the electronic structure on its adsorption strength was studied. This provided a novel and well-considered solution and theoretical guidance for the design of rational composition and structurally superior tandem catalysts.

Photocatalytic ethane conversion on rutile TiO2(110): identifying the role of the ethyl radical.

Oxidative dehydrogenation of ethane (C2H6, ODHE) is a promising approach to producing ethene (C2H4) in the chemical industry. However, the ODHE needs to be operated at a high temperature, and realizing the ODHE under mild conditions is still a big challenge. Herein, using photocatalytic ODHE to obtain C2H4 has been achieved successfully on a model rutile(R)-TiO2(110) surface with high selectivity. Initially, the C2H6 reacts with hole trapped OTi- centers to produce ethyl radicals , which can be precisely detected by a sensitive TOF method, and then the majority of the radicals spontaneously dehydrogenate into C2H4 without another photo-generated hole. In addition, parts of the radicals rebound with diversified surface sites to produce C2 products via migration along the surface. The mechanistic model built in this work not only advances our knowledge of the C-H bond activation and low temperature C2H6 conversion, but also provides new opportunities for realizing the ODHE with high C2H4 efficiency under mild conditions.

Origin of copper as a unique catalyst for C-C coupling in electrocatalytic CO2 reduction.

High yields of C2 products through electrocatalytic CO2 reduction (eCO2R) can only be obtained using Cu-based catalysts. Here, we adopt the generalized frontier molecular orbital (MO) theory based on first-principles calculations to identify the origin of this unique property of Cu. We use the grand canonical ensemble (or fixed potential) approach to ensure that the calculated Fermi level, which serves as the frontier orbital of the metal catalyst, accurately represents the applied electrode potentials. We determine that the key intermediate OCCO assumes a U-shape configuration with the two C atoms bonded to the Cu substrate. We identify the frontier MOs that are involved in the C-C coupling. The good alignment of the Fermi level of Cu with these frontier MOs is perceived to account for the excellent catalytic performance of Cu for C-C coupling. It is expected that these new insights could provide useful guidance in tuning Cu-based catalysts as well as designing non-Cu catalysts toward high-efficiency eCO2R.

Suppressing product crossover and C–C bond cleavage in a glycerol membrane electrode assembly reformer

An innovative acid–alkali asymmetric cell design to suppress the crossover of liquid products and facilitate glycerol oxidation reaction. It can also impede C–C bond cleavage to promote high-value C3 products generation and reduce carbon emission.

Bismuth single-atom alloying of palladium nanosheets promotes selective electrochemical valorization of glycerol to C3 products

Bi atoms dispersed on Pd nanosheets promote electrochemical glycerol oxidation to C3 products by modulating the Pd electronic structure and lowering the adsorption energy of reaction intermediates.

Tuneable C3 product selectivity of glycerol electrooxidation on cubic and dendritic Pt nanocatalysts.

Glycerol, being an abundant and cheap by-product of biodiesel production, has emerged as a raw material that can be recycled into value-added compounds. In the present study, Pt nanoparticles of cubic (PtCUBE) and dendritic (PtDEND) morphologies were investigated as catalysts for the glycerol electrooxidation reaction (GEOR) at 20 °C. To optimise the electrocatalytic performance and GEOR selectivity towards three-carbon (C3) products, namely lactate, glycerate, and tartronate, the effects of morphology, electrolyte composition, and applied potential were studied. At low glycerol concentrations, C-C bond cleavage was more favoured, especially on PtDEND. Both PtCUBE and PtDEND showed high C3 product selectivity up to 91% at 0.67 V vs. RHE, with lactate reaching a maximum selectivity of 68% on PtCUBE, which also exhibited the best mass and specific activities compared to PtDEND.

K+ selectivity modulation in non-aqueous CO2 electroreduction on lead catalysts: from oxalic to tartaric acid production

Modulating potassium ions and the proton concentration in the catholyte regulates the faradaic efficiency and selectivity of a Pb plate electrode in non-aqueous media, forming a C4 product from CO2 reduction.

Electrochemical CO2 reduction reaction on TM-C3N5 for C1 products: A DFT study

In the electrochemical CO2 reduction reaction (CO2RR), transition metal atoms embedded in carbon and nitrogen materials are widely seen as highly efficient catalysts because of their excellent catalytic activity and...

Four-electron reduction of CO2: from formaldehyde and acetal synthesis to complex transformations.

The expansive and dynamic field of the CO2 Reduction Reaction (CO2RR) seeks to harness CO2 as a sustainable carbon source or energy carrier. While significant progress has been made in two, six, and eight-electron reductions of CO2, the four-electron reduction remains understudied. This review fills this gap, comprehensively exploring CO2 reduction into formaldehyde (HCHO) or acetal-type compounds (EOCH2OE, with E = [Si], [B], [Zr], [U], [Y], [Nb], [Ta] or -R) using various CO2RR systems. These encompass (photo)electro-, bio-, and thermal reduction processes with diverse reductants. Formaldehyde, a versatile C1 product, is challenging to synthesize and isolate from the CO2RR. The review also discusses acetal compounds, emphasizing their significance as pathways to formaldehyde with distinct reactivity. Providing an overview of the state of four-electron CO2 reduction, this review highlights achievements, challenges, and the potential of the produced compounds - formaldehyde and acetals - as sustainable sources for valuable product synthesis, including chiral compounds.

Theoretical study of transition metal-doped β12 borophene as a new single-atom catalyst for carbon dioxide electroreduction.

The electrocatalytic carbon dioxide reduction reaction (CO2RR) presents a viable and cost-effective approach for the elimination of CO2 by transforming it into valuable products. Nevertheless, this process is impeded by the absence of exceptionally active and stable catalysts. Herein, a new type of electrocatalyst of transition metal (TM)-doped β12-borophene (TM@β12-BM) is investigated via density functional theory (DFT) calculations. Through comprehensive screening, two promising single-atom catalysts (SACs), Sc@β12-BM and Y@β12-BM, are successfully identified, exhibiting high stability, catalytic activity and selectivity for the CO2RR. The C1 products methane (CH4) and methanol (CH3OH) are synthesized with limiting potentials (UL) of -0.78 V and -0.56 V on Sc@β12-BM and Y@β12-BM, respectively. Meanwhile, CO2 is more favourable for reduction into the C2 product ethanol (CH3CH2OH) compared to ethylene (C2H4) via C-C coupling on these two SACs. More importantly, the dynamic barriers of the key C-C coupling step are 0.53 eV and 0.73 eV for the "slow-growth" sampling approach in the explicit water molecule model. Furthermore, Sc@β12-BM and Y@β12-BM exhibit higher selectivity for producing C1 compounds (CH4 and CH3OH) than C2 (CH3CH2OH) in the CO2RR. Compared with Sc@β12-BM, Y@β12-BM demonstrates superior inhibition of the competitive hydrogen evolution reaction (HER) in the liquid phase. These results not only demonstrate the great potential of SACs for direct reduction of CO2 to C1 and C2, but also help in rationally designing high-performance SACs.

Recent progress of heterogeneous catalysts for transfer hydrogenation under the background of carbon neutrality.

Under the background of carbon neutrality, the direct conversion of greenhouse CO2 to high value added fuels and chemicals is becoming an important and promising technology. Among them, the generation of liquid C1 products (formic acid and methanol) has made great progress; nevertheless, it encounters the problem of how to use it efficiently to solve the overcapacity issue. In this review, we suggest that the catalytic transfer hydrogenation using formic acid and methanol as the hydrogen sources is a critical and potential route for the substitution for the fossil fuel-derived H2 to generate essential bulk and fine chemicals. We mainly focus on summarizing the recent progress of heterogeneous catalysts in such reactions, including thermal- and photo-catalytic processes. Finally, we also propose some challenges and opportunities for this development.

Universal synthesis of pure-phase IB-group Sn-based alloys with modulable electrocatalytic CO2 reduction products.

We present a universal preparation method for synthesizing a range of pure-phase IB-group Sn-based alloy catalysts (Cu3Sn, Ag4Sn, and AuSn) for electrochemical reduction of CO2 to C1 product. The selectivity can be widely adjusted by altering metal composition and potential, improving the understanding of the structure-activity relationship in various Sn-based alloys.