The authors report enhanced poly(3-hexylthiophene) (P3HT):methanofullerene (PCBM) bulk-heterojunction photovoltaic cells via 1,2-dichlorobenzene (DCB) vapor treatment and thermal annealing. DCB vapor treatment can induce P3HT self-organizing into ordered structure leading to enhanced absorption and high hole mobility. Further annealing the device at a high temperature, PCBM molecules begin to diffuse into aggregates and together with the ordered P3HT phase form bicontinuous pathways in the entire layer for efficient charge separation and transport. Compared to the control device that is merely annealed, optical absorption, short-circuit current, and power conversion efficiency are increased for the DCB vapor-treated cell.

We report a highly sensitive electrochemical sensor for the detection of Hg(2+) ions in aqueous solution by using a thymine (T)-rich, mercury-specific oligonucleotide (MSO) probe and gold nanoparticles (Au NPs)-based signal amplification. The MSO probe contains seven thymine bases at both ends and a "mute" spacer in the middle, which, in the presence of Hg(2+), forms a hairpin structure via the Hg(2+)-mediated coordination of T-Hg(2+)-T base pairs. The thiolated MSO probe is immobilized on Au electrodes to capture free Hg(2+) in aqueous media, and the MSO-bound Hg(2+) can be electrochemically reduced to Hg(+), which provides a readout signal for quantitative detection of Hg(2+). This direct immobilization strategy leads to a detection limit of 1 microM. In order to improve the sensitivity, MSO probe-modified Au NPs are employed to amplify the electrochemical signals. Au NPs are comodified with the MSO probe and a linking probe that is complementary to a capture DNA probe immobilized on gold electrodes. We demonstrated that this Au NPs-based sensing strategy brings about an amplification factor of more than 3 orders of magnitude, leading to a limit of detection of 0.5 nM (100 ppt), which satisfactorily meets the sensitivity requirement of U.S. Environmental Protection Agency (EPA). This Au NPs-based Hg(2+) sensor also exhibits excellent selectivity over a spectrum of interference metal ions. Considering the high sensitivity and selectivity of this sensor, as well as the cost-effective and portable features of electrochemical techniques, we expect this Au NPs amplified electrochemical sensor will be a promising candidate for field detection of environmentally toxic mercury.

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Hydrogen‐treated TiO2 nanotube (H–TNT) arrays serve as highly ordered nanostructured electrode supports, which are able to significantly improve the electrochemical performance and durability of fuel cells. The electrical conductivity of H–TNTs increases by approximately one order of magnitude in comparison to air‐treated TNTs. The increase in the number of oxygen vacancies and hydroxyl groups on the H–TNTs help to anchor a greater number of Pt atoms during Pt electrodeposition. The H–TNTs are pretreated by using a successive ion adsorption and reaction (SIAR) method that enhances the loading and dispersion of Pt catalysts when electrodeposited. In the SIAR method a Pd activator can be used to provide uniform nucleation sites for Pt and leads to increased Pt loading on the H‐TNTs. Furthermore, fabricated Pt nanoparticles with a diameter of 3.4 nm are located uniformly around the pretreated H–TNT support. The as‐prepared and highly ordered electrodes exhibit excellent stability during accelerated durability tests, particularly for the H–TNT‐loaded Pt catalysts that have been annealed in ultrahigh purity H2 for a second time. There is minimal decrease in the electrochemical surface area of the as‐prepared electrode after 1000 cycles compared to a 68 % decrease for the commercial JM 20 % Pt/C electrode after 800 cycles. X‐ray photoelectron spectroscopy shows that after the H–TNT‐loaded Pt catalysts are annealed in H2 for the second time, the strong metal–support interaction between the H–TNTs and the Pt catalysts enhances the electrochemical stability of the electrodes. Fuel‐cell testing shows that the power density reaches a maximum of 500 mW cm−2 when this highly ordered electrode is used as the anode. When used as the cathode in a fuel cell with extra‐low Pt loading, the new electrode generates a specific power density of 2.68 kW gPt−1. It is indicated that H–TNT arrays, which have highly ordered nanostructures, could be used as ordered electrode supports.

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The marriage of non-fullerene acceptors (NFAs) and ternary solar cell architecture has brought about great advances in organic photovoltaics. The primary effort, however, has been focusing on low-bandgap NFAs that exploit complementary absorption and energy-level cascade. Here we report a wide-bandgap NFA IDT-T that functions as an energy-level mediator, a fluorescence resonance energytransfer donor, an electron acceptor, and a crystallization modulator, which contribute synergistically in a ternary blend to yield high organic photovoltaic device performance.