No abstract

Additive and antisolvent engineering strategies are outstandingly efficient in enhancing perovskite quality, photovoltaic performance, and stability of perovskite solar cells (PSCs). In this work, an effective approach is applied by coupling the antisolvent mixture and multi-functional additive procedures, which is recognized as antisolvent additive engineering (AAE). The graphene quantum dots functionalized with amide (AGQDs), which consists of carbonyl, amine, and long hydrophobic alkyl chain functional groups, are added to the antisolvent mixture of toluene (T) and hexane (H) as an efficient additive to form the CH3NH3PbI3 (MAPI):AGQDs graded heterojunction structure. A broad range of analytical techniques, including scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, space charge limited current, UV–visible spectroscopy, external quantum efficiency, and time-of-flight secondary ion mass spectrometry, are used to investigate the effect of AAE treatment with AGQDs on the quality of perovskite film and performance of the PSCs. Importantly, not only a uniform and dense perovskite film with hydrophobic property is obtained but also defects on the perovskite surface are significantly passivated by the interaction between AGQDs and uncoordinated Pb2+. As a result, an enhanced power conversion efficiency (PCE) of 19.10% is achieved for the champion PSCs treated with AGQD additive, compared to the PCE of 16.00% for untreated reference PSCs. In addition, the high-efficiency PSCs based on AGQDs show high stability and maintain 89% of their initial PCE after 960 h in ambient conditions.

We report here the fabrication of ruthenium/platinum (RuPt) bimetallic monolayer coated on a nanoporous gold film electrode (RuPtNPGF) by underpotential deposition of copper (UPD) with the Cu layer then replaced spontaneously by Ru and Pt. The present method could provide a very low RuPt-loading electrode and the results demonstrated that ultra thin RuPt coating behaved efficiently as a bimetallic nanostructure RuPt for electrocatalytic oxidation of methionine. The structure and morphology of the catalyst were defined by using energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM), respectively. The RuPtNPGF electrode displayed good performance along with low working potential, high selectivity, and a low detection limit for the oxidation of methionine. Whereas at the surface of the bare electrode a redox peak for methionine cannot be observed, a sharp anodic peak at a potential of 0.73 V (vs. Ag/AgCl) in pH ¼ 7.0 is obtained using the prepared RuPtNPGF electrode. Under optimized conditions differential pulse voltammetry (DPV) of methionine showed two linear ranges for the determination of methionine: 6-105 nmol L À1 and 3-102 mmol L À1 with a detection limit of 2 nmol L À1 . Finally, the proposed sensor was successfully applied for the determination of methionine in human urine, with satisfactory results.