Sensing from the ultraviolet-visible to the infrared is critical for a variety of industrial and scientific applications. Today, gallium nitride-, silicon-, and indium gallium arsenide--based detectors are used for different sub-bands within the ultraviolet to near-infrared wavelength range. We demonstrate polymer photodetectors with broad spectral response (300 to 1450 nanometers) fabricated by using a small-band-gap semiconducting polymer blended with a fullerene derivative. Operating at room temperature, the polymer photodetectors exhibit detectivities greater than 10(12) cm Hz(1/2)/W and a linear dynamic range over 100 decibels. The self-assembled nanomorphology and device architecture result in high photodetectivity over this wide spectral range and reduce the dark current (and noise) to values well below dark currents obtained in narrow-band photodetectors made with inorganic semiconductors.

Photoinduced electron transfer is observed in polymer bulk heterojunction solar cells with very small interfacial energy offset. The results imply that open circuit voltage values close to the band gap of the semiconducting polymer should be possible for polymer bulk heterojunction solar cells just as for inorganic solar cells.

Atomically dispersed metal catalysts with well‐defined structures have been the research hotspot in heterogeneous catalysis because of their high atomic utilization efficiency, outstanding activity, and selectivity. Dual‐atomic‐site catalysts (DASCs), as an extension of single‐atom catalysts (SACs), have recently drawn surging attention. The DASCs possess higher metal loading, more sophisticated and flexible active sites, offering more chance for achieving better catalytic performance, compared with SACs. In this review, recent advances on how to design new DASCs for enhancing energy catalysis will be highlighted. It will start with the classification of marriage of two kinds of single‐atom active sites, homonuclear DASCs and heteronuclear DASCs according to the configuration of active sites. Then, the state‐of‐the‐art characterization techniques for DASCs will be discussed. Different synthetic methods and catalytic applications of the DASCs in various reactions, including oxygen reduction reaction, carbon dioxide reduction reaction, carbon monoxide oxidation reaction, and others will be followed. Finally, the major challenges and perspectives of DASCs will be provided.

The deposition and re-entrainment behaviors of five sizes of carboxylate-modified microspheres (ranging from 0.1 to 2.0 microm) were examined both in porous media and impinging jet systems under a variety of environmentally relevant pore fluid velocities (2-8 m day-'), and in both the absence and the presence of an energy barrier to deposition. The magnitudes of the deposition efficiencies were compared among the porous media and impinging jet systems under equivalent fluid velocities, solution chemistries, and surface chemistries. The observed deposition efficiencies were factors of about 5 to 50 greater in the porous media relative to the impinging jet across the entire size range of microspheres examined, demonstrating that this excess deposition in porous media is relevant to a wide range of colloid sizes. The magnitude of excess deposition increased with increasing fluid velocity, and was greatest for the smallest colloids (0.1 microm). A range between 15% and 40% of the excess retained colloids were released upon introduction of low ionic strength solution, indicating that they were retained via secondary energy minima without direct contact with the grain surfaces. The observations indicate that pore geometry is a critical governor of colloid deposition in the presence of an energy barrier, even in porous media composed of spherical collectors. A portion of this excess deposition results from retention in flow stagnation zones.

The nature of the primary photoexcitations in semiconducting single-walled carbon nanotubes ͑S-SWCNTs͒ is of strong current interest. We have studied the emission spectra of S-SWCNTs and two different -conjugated polymers in solutions and films, and have also performed ultrafast pump-probe spectroscopy on these systems with unprecedented spectral range from 0.1 to 2.6 eV. The emission spectra relative to the absorption bands are very similar in S-SWCNTs and polymers, with redshifted photoluminescence in films showing exciton migration. We also found that the transient excited state spectra of both polymers and SWCNTs contain two prominent photoinduced absorption ͑PA͒ bands ͑PA 1 and PA 2 ͒ that are due to photogenerated excitons; in the polymers these PA bands are correlated with a stimulated emission band, which is absent in the S-SWCNTs. In order to understand the similarities in the PA spectra we have performed theoretical calculations of excited state absorptions in -conjugated polymers as well as S-SWCNTs within the same correlated electron Hamiltonian. We find strong similarities in the excitonic energy spectra of these two classes of quasi-one-dimensional materials, although there exist also subtle differences such as the occurrence of dark excitons below the optical excitons in the S-SWCNTs. In the polymers PA 1 is an excited state absorption from the optical exciton to a two-photon exciton that occurs below the continuum band threshold. In the S-SWCNTs PA 1 occurs from both the optical exciton and the dark exciton, to final states which are close in energy and again below the continuum band threshold. PA 1 therefore gives the lower limit of the binding energy of the lowest optical exciton in both -conjugated polymers and S-SWCNTs. The binding energy of lowest exciton that belongs to the widest S-SWCNTs with diameters ജ1 nm in films is 0.3-0.4 eV, as determined by both experimental and theoretical methods.