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1. Metal‐Organic‐Framework‐Based Electrochemical Nanosensor for Hydrogen Peroxide

   https://doi.org/10.1002/celc.202200373  

   Hesari, Mahdi; Jia, Rui; Mirkin, Michael_V (June 2022, ChemElectroChem)

   Abstract Electrochemical applications of metal organic frameworks (MOFs) are of considerable current interest. Due to the large surface area exposed to solution, MOFs are potentially useful electrode materials for sensing inner‐sphere analytes, such as reactive oxygen species. Herein, we electrodeposited copper benzene tricarboxylate MOF (HKUST‐1) into the cavity of an open carbon nanopipette (CNP) to produce a CNP‐MOF nanoelectrode. Unlike electronically conductive metal or carbon electrodes, the electrochemical response of CNP–MOFs relies on oxidation/reduction of Cu(I)/Cu(II) nodes in the porous nanostructure. Nevertheless, sigmoidal steady‐state voltammograms with a well‐defined plateau current have been recorded for simple redox mediators, for example, ferrocenemethanol. A linear calibration curve obtained for the hydrogen peroxide reduction suggests that CNP–MOFs can potentially be useful as nanosensors for peroxide. 

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2. Perovskite Photocatalytic CO ₂ Reduction or Photoredox Organic Transformation?

   https://doi.org/10.1002/anie.202205572  

   San Martin, Jovan; Dang, Nhu; Raulerson, Emily; Beard, Matthew C.; Hartenberger, Joseph; Yan, Yong (August 2022, Angewandte Chemie International Edition)

   Abstract Metal‐halide perovskites have been explored as photocatalysts for CO₂reduction. We report that perovskite photocatalytic CO₂reduction in organic solvents is likely problematic. Instead, the detected products (i.e., CO) likely result from a photoredox organic transformation involving the solvent. Our observations have been validated using isotopic labeling experiments, band energy analysis, and new control experiments. We designed a typical perovskite photocatalytic setup in organic solvents that led to CO production of up to ≈1000 μmol g⁻¹ h⁻¹. CO₂reduction in organic solvents must be studied with extra care because photoredox organic transformations can produce orders of magnitude higher rate of CO or CH₄than is typical for CO₂reduction routes. Though CO₂reduction is not likely to occur, in situ CO generation is extremely fast. Hence a suitable system can be established for challenging organic reactions that use CO as a feedstock but exploit the solvent as a CO surrogate. 

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3. Phosphorus rather than nitrogen enhances CO ₂ emissions in tropical forest soils: Evidence from a laboratory incubation study

   https://doi.org/10.1111/ejss.12885  

   Hui, Dafeng; Porter, Wesley; Phillips, Jana_R; Aidar, Marcos_PM; Lebreux, Steven_J; Schadt, Christopher_W; Mayes, Melanie_A (January 2020, European Journal of Soil Science)

   Abstract Ecosystem functional responses such as soil CO₂emissions are constrained by microclimate, available carbon (C) substrates and their effects upon microbial activity. In tropical forests, phosphorus (P) is often considered as a limiting factor for plant growth, but it is still not clear whether P constrains microbial CO₂emissions from soils. In this study, we incubated seven tropical forest soils from Brazil and Puerto Rico with different nutrient addition treatments (no addition, Control; C, nitrogen (N) or P addition only; and combined C, N and P addition (CNP)). Cumulative soil CO₂emissions were fit with a Gompertz model to estimate potential maximum cumulative soil CO₂emission (C_m) and the rate of change of soil C decomposition (k). Quantitative polymerase chain reaction (qPCR) was conducted to quantify microbial biomass as bacteria and fungi. Results showed that P addition alone or in combination with C and N enhancedC_m, whereas N addition usually reducedC_m, and neither N nor P affected microbial biomass. Additions of CNP enhancedk, increased microbial abundances and altered fungal to bacterial ratios towards higher fungal abundance. Additions of CNP, however, tended to reduceC_mfor most soils when compared to C additions alone, suggesting that microbial growth associated with nutrient additions may have occurred at the expense of C decomposition. Overall, this study demonstrates that soil CO₂emission is more limited by P than N in tropical forest soils and those effects were stronger in soils low in P. HighlightsA laboratory incubation study was conducted with nitrogen, phosphorus or carbon addition to tropical forest soils. Soil CO₂emission was fitted with a Gompertz model and soil microbial abundance was quantified using qPCR. Phosphorus addition increased model parametersC_mand soil CO₂emission, particularly in the Puerto Rico soils. Soil CO₂emission was more limited by phosphorus than nitrogen in tropical forest soils. 

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4. Hybrid Organic‐Inorganic Heterogeneous Interfaces for Electrocatalysis: A Theoretical Study of CO ₂ Reduction to C ₂

   https://doi.org/10.1002/cctc.202101224  

   Wan, Mingyu; Gu, Zhiyong; Che, Fanglin (December 2021, ChemCatChem)

   Abstract Hybrid organic‐inorganic heterogeneous catalytic interfaces, where traditional catalytic materials are modified with self‐assembled monolayers (SAMs), create promising features to control a wide range of catalytic processes through the design of dual organic‐inorganic active sites and the induced confinement effect. To provide a fundamental insight, we investigated CO₂electroreduction into valuable C₂chemicals (CO₂RR‐to‐C₂) over SAM‐modulated Cu. Our theoretical results show that 1/4 monolayer aminothiolates improve the stability, activity and selectivity of CO₂RR‐to‐C₂by: (1) decreasing surface energy to suppress surface reconstruction; (2) facilitating CO₂activation and C−C coupling through dual organic‐inorganic (i. e., −NH, Cu) active sites; (3) promoting C−C coupling via confinement effects that enlarge the adsorption energy difference between CO^*and COH^*; (4) inducing local electric fields to Cu surface and changing its dipole moment and polarizability to be in favor of C−C coupling under electrode/electrolyte interfacial electric field. 

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5. Non‐Aqueous Electrochemical CO ₂ Reduction to Multivariate C ₂ ‐Products Over Single Atom Catalyst at Current Density up to 100 mA cm ⁻²

   https://doi.org/10.1002/smll.202408010  

   Bhawnani, Rajan_R; Sartape, Rohan; Gande, Vamsi_V; Barsoum, Michael_L; Kallon, Elias_M; Reis, Roberto_dos; Dravid, Vinayak_P; Singh, Meenesh_R (December 2024, Small)

   Abstract Electrochemical CO₂reduction reaction (CO₂‐RR) in non‐aqueous electrolytes offers significant advantages over aqueous systems, as it boosts CO₂solubility and limits the formation of HCO₃⁻and CO₃²⁻anions. Metal–organic frameworks (MOFs) in non‐aqueous CO₂‐RR makes an attractive system for CO₂capture and conversion. However, the predominantly organic composition of MOFs limits their electrical conductivity and stability in electrocatalysis, where they suffer from electrolytic decomposition. In this work, electrically conductive and stable Zirconium (Zr)‐based porphyrin MOF, specifically PCN‐222, metalated with a single‐atom Cu has been explored, which serves as an efficient single‐atom catalyst (SAC) for CO₂‐RR. PCN‐ 222(Cu) demonstrates a substantial enhancement in redox activity due to the synergistic effect of the Zr matrix and the single‐atom Cu site, facilitating complete reduction of C₂species under non‐aqueous electrolytic conditions. The current densities achieved (≈100 mA cm⁻²) are 4–5 times higher than previously reported values for MOFs, with a faradaic efficiency of up to 40% for acetate production, along with other multivariate C₂products, which have never been achieved previously in non‐aqueous systems. Characterization using X‐ray and various spectroscopic techniques, reveals critical insights into the role of the Zr matrix and Cu sites in CO₂reduction, benchmarking PCN‐222(Cu) for MOF‐based SAC electrocatalysis. 

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