Editorial: Special Issue on “Emerging Nanostructured Catalytic Materials for Energy and Environmental Applications”

In recent years, there has been a great demand for the rational design and development of novel catalytic materials at the nanoscale (1–100 nm), with a view to more accurately and efficiently control reaction pathways due to their high surface area and intrinsic properties [...]

Real-Time Imaging of Nanoscale Electrochemical Ni Etching under Thermal Conditions

The ability to vary the temperature of an electrochemical cell provides opportunities to control reaction rates and pathways and to drive processes that are inaccessible at ambient temperature. Here, we...

Verification of an Accommodative Response for Depth Measurement of Floating Hologram Using a Holographic Optical Element

Floating holograms using holographic optical element screens differ from existing systems because they can float 2D images in the air and provide a sense of depth. Until now, the verification of such displays has been conducted only on the system implementation, and only the diffraction efficiency and angle of view of the hologram have been verified. Although such displays can be directly observed with the human eye, the eye’s control ability has not been quantitatively verified. In this study, we verified that the focus of the observer coincided with the appropriate depth value determined with experiments. This was achieved by measuring the amount of control reaction from the perspective of the observer on the image of the floating hologram using a holographic optical element (HOE). An autorefractor was used, and we confirmed that an image with a sense of depth can be observed from the interaction of the observer’s focus and convergence on the 2D floating image using a HOE. Thus, the realization of content with a sense of depth of 2D projected images using a HOE in terms of human factors was quantitatively verified.

Using light intensity to control reaction kinetics and reversibility in photomechanical crystals

The chemical and mechanical recovery rates of crystalline 4-fluoro-9-anthracenecarboxylic acid, a thermally reversible photomechanical material, can be controlled by both the intensity of the photodimerization pulse and the use of a weak hold beam.

Supramolecular Tuning Enables Selective Oxygen Reduction Catalyzed by Cobalt Porphyrins for Direct Electrosynthesis of Hydrogen Peroxide

<div> <div> <div> <p>We report a supramolecular design strategy for promoting the selective reduction of O2 for direct electrosynthesis of H2O2. Specifically, we utilized cobalt tetraphenylporphyrin (Co-TPP), a non-selective oxygen reduction reaction (ORR) catalyst, as a building block to assemble the permanently porous supramolecular cage Co-PB-1(6) bearing six Co-TPP subunits connected through twenty-four imine bonds. Reduction of these imine linkers to amines yields the more flexible porous cage Co-rPB-1(6). Both Co-PB-1(6) and Co-rPB-1(6) cages produce 90-100% H2O2 from electrochemical ORR catalysis in neutral pH water, and we attribute this high selectivity to site isolation of the discrete molecular units, as the analogous Co-TPP monomer generates only a 50% mixture of H2O2 and H2O from electrochemical ORR under the same conditions. The ability to control reaction selectivity in supramolecular structures beyond traditional host-guest interactions offers new opportunities for designing such architectures for a broader range of catalytic applications. </p> </div> </div> </div>

Re-Programming Hydrogel Properties using a Fuel-driven Reaction Cycle

Nature uses catalysis as an indispensable tool to control assembly and reaction cycles in vital non-equilibrium supramolecular processes. For instance, enzymatic methionine oxidation regulates actin (dis)assembly, and catalytic guanosine triphosphate hydrolysis is found in tubulin (dis)assembly. Here we present a completely artificial reaction cycle which is driven by a chemical fuel that is catalytically obtained from a ‘pre-fuel’. The reaction cycle controls the disassembly and re-assembly of a hydrogel, where the rate of pre-fuel turnover dictates the morphology as well as the mechanical properties. By adding additional fresh aliquots of fuel and removing waste, the hydrogels can be re-programmed time after time. Overall, we show how catalysis can control fuel generation to control reaction / assembly kinetics and materials properties in life-like non-equilibrium systems.

Re-Programming Hydrogel Properties using a Fuel-driven Reaction Cycle

Nature uses catalysis as an indispensable tool to control assembly and reaction cycles in vital non-equilibrium supramolecular processes. For instance, enzymatic methionine oxidation regulates actin (dis)assembly, and catalytic guanosine triphosphate hydrolysis is found in tubulin (dis)assembly. Here we present a completely artificial reaction cycle which is driven by a chemical fuel that is catalytically obtained from a ‘pre-fuel’. The reaction cycle controls the disassembly and re-assembly of a hydrogel, where the rate of pre-fuel turnover dictates the morphology as well as the mechanical properties. By adding additional fresh aliquots of fuel and removing waste, the hydrogels can be re-programmed time after time. Overall, we show how catalysis can control fuel generation to control reaction / assembly kinetics and materials properties in life-like non-equilibrium systems.

Supramolecular Tuning Enables Selective Oxygen Reduction Catalyzed by Cobalt Porphyrins for Direct Electrosynthesis of Hydrogen Peroxide

<div> <div> <div> <p>We report a supramolecular design strategy for promoting the selective reduction of O2 for direct electrosynthesis of H2O2. Specifically, we utilized cobalt tetraphenylporphyrin (Co-TPP), a non-selective oxygen reduction reaction (ORR) catalyst, as a building block to assemble the permanently porous supramolecular cage Co-PB-1(6) bearing six Co-TPP subunits connected through twenty-four imine bonds. Reduction of these imine linkers to amines yields the more flexible porous cage Co-rPB-1(6). Both Co-PB-1(6) and Co-rPB-1(6) cages produce 90-100% H2O2 from electrochemical ORR catalysis in neutral pH water, and we attribute this high selectivity to site isolation of the discrete molecular units, as the analogous Co-TPP monomer generates only a 50% mixture of H2O2 and H2O from electrochemical ORR under the same conditions. The ability to control reaction selectivity in supramolecular structures beyond traditional host-guest interactions offers new opportunities for designing such architectures for a broader range of catalytic applications. </p> </div> </div> </div>