Heterogeneous Catalysis for Water Oxidation by an Iridium Complex Immobilized on Bipyridine‐Periodic Mesoporous Organosilica

Abstract

Heterogenization of metal-complex catalysts for water oxidation without loss of their catalytic activity is important for the development of devices simulating photosynthesis. In this study, efficient heterogeneous iridium complexes for water oxidation were prepared using bipyridine-bridged periodic mesoporous organosilica (BPy-PMO) as a solid chelating ligand. The BPy-PMO-based iridium catalysts (Ir-BPy-PMO) were prepared by postsynthetic metalation of BPy-PMO and characterized through physicochemical analyses. The Ir-BPy-PMOs showed high catalytic activity for water oxidation. The turnover frequency (TOF) values for Ir-BPy-PMOs were one order of magnitude higher than those of conventional heterogeneous iridium catalysts. The reusability and stability of Ir-BPy-PMO were also examined, and detailed characterization was conducted using powder X-ray diffraction, nitrogen adsorption, (13) C DD MAS NMR spectroscopy, TEM, and XAFS methods.

Volta Potential Evolution of Intermetallics in Aluminum Alloy Microstructure Under Thin Aqueous Adlayers: A combined DFT and Experimental Study

“…In the SEM images, all precipitates show brighter contrast than the matrix except for Mg 2 Si, which exhibits a darker contrast due to a lower mean atomic number than the matrix. All IMP's except for Al 2 Cu contain Si, Fe, Mn, and Cr, (Fig.…”

“…The microstructure of the alloy contains Al 4 2 Si is low, having a fraction of ≈ 0.1 vol%. In the SEM images, all precipitates show brighter contrast than the matrix except for Mg 2 Si, which exhibits a darker contrast due to a lower mean atomic number than the matrix.…”

“…The literature includes experimental and theoretical studies in diverse research areas such as heterogeneous catalysis (Refs. [1,2] are examples of recent publications), meteorology [3,4], geology [5,6], physical chemistry [7,8], solar energy conversion [9][10][11], pharmacy [12], atmospheric chemistry [13], electrochemistry [14,15], tribology [16,17], and corrosion science [18,19]. Advancements in experimental and computational techniques have resulted in considerable progress in our fundamental view of water-solid interactions, and the research field has been summarized in a few most comprehensive reviews [20][21][22].…”

“…In the current study these efforts have advanced one step further by comparing theoreticallydeduced Volta potential differences calculated by DFT with local Volta potential differences measured on a commercial aluminum alloy (AA6063-T5) by SKPFM. DFT has been used to obtain Volta potential differences between two IMP's (Mg 2 Si and Al 2 Cu with different surface atomic terminals) and the aluminum matrix in the presence of up to two ML's of water. SKPFM was performed in the presence of wellcontrolled humidified air on a commercial aluminum alloy (AA6063-T5) to measure the difference in Volta potentials between the same IMP's and the surrounding aluminum matrix at different RH.…”

Palladium Nanoparticles Tethered in Amine-Functionalized Hypercrosslinked Organic Tubes as an Efficient Catalyst for Suzuki Coupling in Water

“…In fact, the main advantage of POPs with its competitive porous support viz. metal organic frameworks (MOFs) [10] and periodic mesoporous organosilica (PMOs) [11,12] is its stability in drastic reaction conditions, which has been immensely highlighted as POPs have shown usability in water medium for catalysis.…”