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Amine-containing polyelectrolytes such as polyethyleneimine (PEI) are commonly used as cathode interfacial materials (CIMs); however, they are rarely found in non-fullerene acceptor (NFA) organic solar cells due to undesirable chemical reactions between PEI and NFAs. Unveiling the nature of these chemical interactions and developing chemically stable amine-containing polyelectrolytes is inevitable for achieving highly efficient and stable NFA organic solar cells. Herein, the reaction between PEI and 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (INCN)-based NFAs was investigated using a model system. 15N-isotope labeling experiments and 2D nuclear magnetic resonance (NMR) studies revealed that the products were generated by the Michael addition reaction and existed as the keto–enol tautomers. Based on the identified undesirable reaction, we developed a series of functionalized PEIs that are compatible with INCN-based NFAs by protecting the reactive amine functional groups. Highly efficient and stable NFA organic solar cells were successfully fabricated by the use of functionalized PEIs with broad work function tunability and improved chemical stability, which led to NFA organic solar cells with high power conversion efficiency (PCE) values of over 15% and thermally stable device operation for more than 360 hours at 100 °C.

For several decades, the key challenge associated with thermochemical hydrogen generation has been the achievement of water splitting and catalyst regeneration at low temperatures while maintaining a reasonably high conversion efficiency over many cycles. Herein, we report low-temperature thermochemical hydrogen generation using hierarchically assembled iron oxide nanoarchitectures. Iron oxide nanoparticles conformally deposited onto a SnO2 nanowire forest allowed the splitting of water molecules and the production of hydrogen gas at temperatures of 400–800 °C, with a high specific gas-forming rate as high as ∼25000 μmol per g per cycle (250 min). More remarkably, deep-ultraviolet photoactivation enabled low-temperature (200 °C) catalyst regeneration and thereby multiple cycles of hydrogen production without any significant coalescence of the oxide nanoparticles nor substantial loss of the water-splitting efficiency. Hierarchically arranged iron oxide nanoarchitectures, in combination with photochemical catalyst regeneration, are promising for practical hydrogen generation by harvesting wasted thermal energy, even at temperatures below 500 °C.

In this research, we report a polypyrrole (PPy) multilayer-laminated cellulose network aimed at the cost-effective removal of aqueous potentially toxic metal ions with high adsorption efficiency and good adsorbent recyclability. The preparation of conformal adsorbent coatings on a fibrous cellulose network was accomplished by performing multiple cycles of simple dip-coating of a non-toxic oxidant and vapor-phase polymerization of PPy. The resultant PPy multilayer-deposited cellulose exhibited stable adhesion between the vapor-deposited PPy and the underlying cellulose support even in a strongly acidic solution. Using this non-hazardous hybrid adsorbent, mercury ions could be efficiently adsorbed over a large pH range with a maximum specific adsorption capacity of 31.689 mg g−1, either in the form of a thick suspended adsorbent for large-scale decontamination or a thin dripper-type membrane for portable water purification. Furthermore, the PPy multilayer-laminated cotton fabric enabled the large-scale repetitive removal of mercury ions (100 ppm, 1 liter) with efficiency above 91%. This study suggests that the PPy-cotton hybrid may serve as a large-scale, economical, and recyclable decontamination platform for efficient removal of highly potentially toxic metal ions (e.g., Hg(II) and Cr(VI)), which could be beneficial for water purification, particularly in resource-limited locations.

Correction for ‘Polypyrrole multilayer-laminated cellulose for large-scale repeatable mercury ion removal’ by Zahid Hanif et al., J. Mater. Chem. A, 2016, 4, 12425–12433.