Inside-and-Out Semiconductor Engineering for CO2 Photoreduction: From Recent Advances to New Trends

Graphitic carbon nitride (g-C3N4), with a moderate band gap (∼2.7 eV), high chemical and thermal stability, has been the hotspot in environmental photocatalysis. However, its performance is still u...

Recent developments of doped g-C3N4 photocatalysts for the degradation of organic pollutants

The conversion of carbon dioxide (CO2) into fuels and value-added products is one of the most significant inventions to address the global warming and energy needs. Photoelectrochemical (PEC) CO2 c...

Photoelectrochemical Conversion of Carbon Dioxide (CO2) into Fuels and Value-Added Products

Stochastic thermodynamics extends the traditional laws of thermodynamics to microscopic systems where thermal and quantum fluctuations cannot be ignored. This review summarizes progress in this field with a look at several experimental and theoretical results and a look toward potential applications in biology and nanotechnology.

https://link.aps.org/pdf/10.1103/PhysRevX.7.021051

Experiments in Stochastic Thermodynamics: Short History and Perspectives

One-step preparation (3D/2D/2D) BiVO4/FeVO4@rGO heterojunction composite photocatalyst for the removal of tetracycline and hexavalent chromium ions in water

The photocatalytic reduction of CO2 into light hydrocarbons using sunlight and water is a challenging reaction involving eight electron transfer steps; nevertheless, it has great potential to address the problem of rising anthropogenic carbon emissions and enable the use of fossil fuels in a sustainable way. Several decades after its first use, TiO2 remains one of the best performing and most durable photocatalysts for CO2 reduction albeit with a poor visible light absorption capacity. We have used flame annealing to improve the response of TiO2 to visible photons and engineered a nanotubular morphology with square-shaped cross-sections in flame-annealed nanotubes. An enhanced CH4 yield was achieved in the photoreduction of CO2 using flame annealed TiO2 nanotubes, and isotope labeled experiments confirmed the reaction products to originate from the CO2 reactant. Flame-annealed TiO2 nanotubes formed in aqueous electrolyte (FANT-aq) yielded 156.5 μmol gcatalyst–1.hr–1 of CH4, which is in the top tier of reported performance values achieved using TiO2 as a stand-alone photocatalyst. This performance resulted because appreciable amounts of CH4 were generated under visible light illumination as well. TiO2 nanotubes exhibited CO2 photoreduction activity up to a wavelength of 620 nm with visible light driven photocatalytic activity peaking at 450 nm for flame annealed TiO2 nanotubes. Isotope labelling studies, using GC–MS and gas-phase FTIR, indicated photoreduction of 13CO2 to 13CH4. The detection of 13CO in the product mixture, and the absence of HCHO and HCOOH provides strong support for the photoreduction proceeding along a carbene pathway. The enhanced CO2 photoreduction performance of FANT-aq is attributed to increased visible light absorption, square morphology, and the presence of rutile as the only crystalline phase with (110) as the dominant plane.

/pdf/high-rate-co2-photoreduction-using-flame-annealed-tio2-sriaaf7lxm.pdf

High rate CO2 photoreduction using flame annealed TiO2 nanotubes

Multidimensional protein-folding dynamics are often probed experimentally by projecting into a single dimension. Single-molecule experiments now verify the idea that folding can be understood in terms of one-dimensional diffusion over a landscape.

Protein folding trajectories can be described quantitatively by one-dimensional diffusion over measured energy landscapes

The nanoscale confinement and coupling of electromagnetic radiation into plexcitonic modes has drawn immense interest because of the innovative possibilities for their application in light harvesting and light emitting devices (LEDs). Plexcitons arise from the coupling between two types of quasiparticles, plasmons and excitons, and can be distinguished by the strength of the coupling into strong and weak coupling regimes. Plexcitons have been used to modulate the rate of Forster-type resonance energy transfer in quantum dot assemblies and enhance the spontaneous emission rate in quantum dot LEDs. The clearest examples of a plexcitonic enhancement of photocatalytic reaction rates have been evidenced in hybrid systems wherein the strongly bound exciton found in 2D sheet-like semiconductors is coupled to the surface plasmon resonance of close-lying noble metal nanoparticles. Plexcitonic photocatalysts and solar cells aim to increase the lifetime of hot carriers and thereby enhance the quantum yields for energy harvesting. Since plexcitonics requires the placement of plasmonic and excitonic components in close proximity with one another to facilitate their coupling, it provides a rich arena for chemists and materials scientists to form deterministic and non-deterministic arrays and heterojunctions involving noble metal thin films and nanostructures, quantum dots and dye molecules. This review summarizes the dynamics of plexcitons in the various composite systems and provides an overview of the latest theoretical and experimental developments in the field of plexcitonics.

/pdf/plexcitonics-fundamental-principles-and-optoelectronic-3mr5v0lsix.pdf

Plexcitonics – fundamental principles and optoelectronic applications

Structural self-assembly in biopolymers, such as proteins and nucleic acids, involves a diffusive search for the minimum-energy state in a conformational free-energy landscape The likelihood of folding proceeding to completion, as a function of the reaction coordinate used to monitor the transition, can be described by the splitting probability, pfold(x) Pfold encodes information about the underlying energy landscape, and it is often used to judge the quality of the reaction coordinate Here, we show how pfold can be used to reconstruct energy landscapes from single-molecule folding trajectories, using force spectroscopy measurements of single DNA hairpins Calculating pfold(x) directly from trajectories of the molecular extension measured for hairpins fluctuating in equilibrium between folded and unfolded states, we inverted the result expected from diffusion over a 1D energy landscape to obtain the implied landscape profile The results agreed well with the landscapes reconstructed by established methods, but, remarkably, without the need to deconvolve instrumental effects on the landscape, such as tether compliance The same approach was also applied to hairpins with multistate folding pathways The relative insensitivity of the method to the instrumental compliance was confirmed by simulations of folding measured with different tether stiffnesses This work confirms that the molecular extension is a good reaction coordinate for these measurements, and validates a powerful yet simple method for reconstructing landscapes from single-molecule trajectories

https://www.pnas.org/content/pnas/112/23/7183.full.pdf

Reconstructing folding energy landscapes from splitting probability analysis of single-molecule trajectories

/pdf/noble-metal-free-visible-light-driven-photocatalysis-using-4uesdg6acg.pdf

Ajay P. Manuel

Papers

High rate CO2 photoreduction using flame annealed TiO2 nanotubes

Protein folding trajectories can be described quantitatively by one-dimensional diffusion over measured energy landscapes

Plexcitonics – fundamental principles and optoelectronic applications

Reconstructing folding energy landscapes from splitting probability analysis of single-molecule trajectories

Noble Metal Free, Visible Light Driven Photocatalysis Using TiO2 Nanotube Arrays Sensitized by P‐Doped C3N4 Quantum Dots