Universal Synthesis of Amorphous Metal Oxide Nanomeshes.

Constructing the pore structures in amorphous metal oxide nanosheets can enhance their electrocatalytic performance by efficiently increasing specific surface areas and facilitating mass transport in electrocatalysis. However, the accurate synthesis for porous amorphous metal oxide nanosheets remains a challenge. Herein, a facile nitrate-assisted oxidation strategy is reported for synthesizing amorphous mesoporous iridium oxide nanomeshes (a-m IrOx NMs) with a pore size of ∼4 nm. X-ray absorption characterizations indicate that a-m IrOx NMs possess stretched Ir─O bonds and weaker Ir-O interaction compared with commercial IrO2. Combining thermogravimetric-fourier transform infrared spectroscopy with differential scanning calorimetry measurements, it is demonstrated that sodium nitrate, acting as an oxidizing agent, is conducive to the formation of amorphous nanosheets, while the NO2 produced by the in situ decomposition of nitrates facilitates the generation of pores within the nanomeshes. As an anode electrocatalyst in proton exchange membrane water electrolyzer, a-m IrOx NMs exhibit superior performance, maintaining a cell voltage of 1.67 V at 1 A cm-2 for 120 h without obvious decay with a low loading (0.4 mgcatalyst cm-2). Furthermore, the nitrate-assisted method is demonstrated to be a general approach to prepare various amorphous metal oxide nanomeshes, including amorphous RhOx, TiOx, ZrOx, AlOx, and HfOx nanomeshes.

Revealing the Molecular Weight Effect on Highly Efficient Polythiophene Solar Cells.

Polythiophenes (PTs) are promising electron donors in organic solar cells (OSCs) due to their simple structures and excellent synthetic scalability. Benefiting from the rational molecular design, the power conversion efficiency (PCE) of PT solar cells has been greatly improved. Herein, five batches of the champion PT (P5TCN-F25) with molecular weights ranging from 30 to 87 kg mol-1 were prepared, and the effect of the molecular weight on the blend film morphology and photovoltaic performance of PT solar cells was systematically investigated. The results showed that the PCEs of the devices improved first and then maintained a high value with the increase of molecular weight, and the highest PCE of 16.7% in binary PT solar cells was obtained. Further characterizations revealed that the promotion in photovoltaic performance mainly comes from finer phase separation structures and more compact molecular packing in the blend film. The best device stabilities were also achieved by polymers with high molecular weights. Overall, this study highlights the importance of optimizing the molecular weight for PTs and offers directions to further improve the PCE of PT solar cells.