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Novel oxygen sensors consisting of a [Ru(bpy)2phen]2+ (bpy: 2,2′‐bipyridyl, phen: phenathroline) portion covalently grafted to a mesostructured silica‐based network are prepared in situ via a sol–gel approach with the help of cetyltrimethylammoniumbromide (CTAB) surfactant. 1,10‐Phenanthroline covalently grafted to 3‐(triethoxysilyl)propyl isocyanate is used as not only the sol–gel precursor but also as the second ligand of the Ru(bpy)2Cl2 · 2H2O complex to prepare the sol–gel‐derived mesostructured silicates for an oxygen sensor. For comparison purposes, the oxygen sensors in which [Ru(bpy)2phen]Cl2 is conventionally physically incorporated into the matrix are also prepared. Elemental analysis, NMR, Fourier transform IR, UV‐vis electronic absorption, luminescence‐intensity quenching Stern–Volmer plots, and excited‐state decay analysis are used to characterize the obtained oxygen sensors. These obtained bulk xerogels and spin‐coated thin films show that the homogeneity and the sensitivity of the covalently grafted samples are superior to those of the physically incorporated ones, and the highest sensitivity is obtained in the mesostructured bulk xerogel. This improvement in oxygen sensitivity is attributed to the increased diffusivity of oxygen in the uniform and nearly parallel porous structure of the Mobil Catalytic Material 41 mesostructured matrix, the enhanced homogeneity results from the covalently grafted propyl group in –Si–(CH2)3– that acts as the fundamental spacer which prevents interaction between the attached RuII complex and the silica matrix, and optimal dispersion in the mesopores during the sol–gel polycondensation. Furthermore, the greatly minimized leaching effect of the sensing molecules could be observed in the covalently grafted system. The covalent grafting strategy presented in this paper provides superior optical oxygen sensors with homogeneous distribution, improved sensitivity, and simplified calibration plots.

Self‐driven photodetectors have wide applications in wireless sensor networks and wearable physiological monitoring systems. While 2D materials have different bandgaps for potential novel application fields, the self‐driven photodetectors are mainly built on PN junctions or heterostructures, whose fabrication involves doping or reliable multiple transfer steps. In this study, a novel metal–semiconductor–metal (MSM) WSe2 photodetector with asymmetric contact geometries is proposed. A high responsivity of 2.31 A W−1 is obtained under zero bias, and a large open‐circuit voltage of 0.42 V is achieved for an MSM photodetector with a large contact length difference. The MSM photodetector can overcome the disadvantage of high dark current in traditional MSM photodetectors. A small dark current of ≈1 fA along with a high detectivity of 9.16 × 1011 Jones is achieved. The working principles and finite element analysis are presented to explain the origin of the self‐driven property and its dependence on the degree of asymmetry.

A generalized surface-initiated photografting procedure, which utilizes polydopamine as a photosensitive initiating layer, allows functionalization of almost any substrate with thin polymer films under sunlight.

CONSPECTUS: Polymer brushes are becoming increasing popular in the chemical literature, because scientists can control their chemical configuration, density, architecture, and thickness down to nanoscale precision with even simple laboratory setups. A polymer brush is made up of a layer of polymers attached to a substrate surface at one end with the other end dangling into a solvent. In a suitable solvent, the polymer chains stretch away from the surface due to both steric and osmotic repulsion between the chain segments. In an inadequate solvent, however, the polymer chains collapse due to enough interior free space after desolvation. This unique class of materials exhibit interesting physicochemical properties at interfaces and have numerous applications from sensing to surface/interface property control. Chemists have made recent advances in surface modification and specific application of polymer brushes, due to both profound mechanistic understanding and synthetic strategies. The commonly used synthetic strategies for generating polymer brushes are surface-initiated polymerizations (SIPs), which resemble planting rice. That is, the assembly of initiator on the surface is similar to transplanting rice seedlings, and the subsequent polymerizations are akin to rice growth. Among different SIP methods, researchers mostly use surface-initiated atom transfer radical polymerization (SI-ATRP) because it provides many advantages in the preparation of well-defined polymer brushes, including easy initiator synthesis, fair control over polymer growth, a "living" end for copolymer grafting, and polymerization in aqueous solution. However, chemists gradually realized that there still room for improvement in this method, since the conventional SI-ATRP method suffers several drawbacks. These include having limited availability on various materials surfaces, rigorous synthetic protocols, heavy consumption and waste of unreacted monomers, and limited ability to control a polymerization process. Moreover, applications of polymer brushes as model surfaces must benefit from the synergistic strategies and profound insights into the fundamental understanding of the polymerization. This is not only to optimize the SI-ATRP process but also to expand the range of monomers, simplify reaction setups, reduce the cost, and ultimately gain control of the synthesis of well-defined polymeric surfaces for material science and engineering. In this Account, we provide an overview of our and others' recent advances in the fabrication of polymer brushes by using SI-ATRP, to promote the widespread application of SI-ATRP and practical applications of the polymer brushes. We aim to provide fundamental mechanistic and synthetic features of SI-ATRP, while emphasizing the various externally applied stimuli mediated catalytic and initiation systems, including electrochemistry, chemical reducing agents, and photochemistry. In addition, we discuss how chemists can advantageously exploit these methods to synthesize functional polymeric surfaces in environ...

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Simulated-sunlight induced atom transfer radical polymerization is used for spatial control over polymer brush growth by in situ photo-generation of the Cu(I) /L activator complex from its higher oxidation state Cu(II) /L deactivator complex using dye sensitized titanium dioxide nano-particles. The polymerization is well controlled under sunlight irradiation. Another attractive feature of this method is the possibility of creating various patterned surfaces of brushes using photomasks. When a nanoporous alumina oxide membrane is used as the template for confinement diffusion of photogenerated Cu(I) /L catalyst, patterns with sub-50 nm resolution are obtained.