Lead sulfide colloidal quantum dot solar cells (CQDSCs), the next generation of photovoltaics, are hampered by non‐radiative recombination induced by defects and an electron‐hole extraction imbalance. CQDSCs have three interfaces: CQD/CQD, electron transport layer (ETL)/CQD, and CQD/hole transport layer (HTL), and modifying one of these interfaces does not fix the problem stated above. Here, coordinated control and passivation of the three interfaces in PbS CQDSCs are presented and it is shown that the synergistic effects may improve charge transport and charge carrier extraction balance and minimize non‐radiative recombination simultaneously. A facile method is developed for epitaxially growing an ultrathin perovskite shell on the CQD surface to passivate the CQD/CQD interface, resulting in CQD absorber layers with long carrier diffusion lengths. With the introduction of organic films with adjustable electrical characteristics, the influence of ETL/CQD interfacial modifications on carrier transport and recombination is investigated. An excessive increase in the electron extraction rate reduces the fill factor and solar efficiency, as discovered. Therefore a modified layer is created at the CQD/HTL interface to promote hole extraction, which enhances charge extraction balance and passivates the interface. Finally, PbS CQDSCs exhibit a power conversion efficiency of 15.45%, a record for Pb chalcogenide CQDSCs.

The application of Pt alloy catalysts for oxygen reduction reactions (ORRs) in proton-exchange membrane fuel cells is severely impeded by base metal leaching, since the produced metal ions can result in the degradation of a Nafion membrane by replacing H + and inducing a Fenton reaction. Doping Pt with nonmetal elements can significantly mitigate such problems due to the relative harmlessness of the corrosion products of anions. Herein, we developed a phosphorus-doping strategy, which can greatly boost the ORR performance of Pt. Phosphorus was introduced into the near-surface of commercial Pt/C (denoted as P NS -Pt/C) via a surfactant-free method. Highangle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and X-ray photoelectron spectrum (XPS) tests indicate that the introduction of phosphorus induced distortion of the Pt lattice and the downshift of the d-band center. In situ electrochemical Fourier transform infrared (FTIR) spectroscopy with adsorbed CO as a molecule probe further revealed that the introduction of phosphorus can lower the adsorption ability. The ORR mass activity of P NS -Pt/C is as high as 1.00 mA μg Pt −

Sulfur-doped multi-walled carbon nanotubes (S-MWCNTs) derived from PEDOT-functionalized MWCNTs can significantly improve the dispersion of supported Pt nanoparticles and enhance their electrocatalytic performance for the MOR.

Upconversion (UC) luminescence materials doped with rare earth ions are extensively investigated as optical temperature probes by the fluorescence intensity ratio technique. However, most Er 3+ -doped materials are still suffering from low sensing sensitivity. In the present study, we attempt to develop high-sensingsensitivity Er 3+ -doped materials based on the thermally coupled energy levels (TCLs) from Stark sublevels as well as the properties at subzero temperatures, for which there is continuous lack of research. Er 3+ /Yb 3+ codoped Ba 3 Y 4 O 9 (BYO) phosphors were produced via a solid-state reaction. Excited by 980 nm, various output colors, including bright green, yellow, and red, in BYO:Er 3+ /Yb 3+ phosphors as well as the relative emission intensities could be regulated through altering Yb 3+ concentrations. Subsequently, on the basis of all 12 pairs of TCLs especially from Stark sublevels of 2 H 11/2 , 4 S 3/2 , and 4 F 9/2 of Er 3+ ions, multiple temperature-sensing performances are evaluated over a wide range of 73−573 K. The results show that the maximum sensitivity of the 2 H 11/2 and 4 S 3/2(1) levels is approximately 1-fold higher than that of traditional TCLs of 2 H 11/2 / 4 S 3/2 at elevated temperature and the maximum sensitivity based on the 2 H 11/2(1) and 2 H 11/2(2) levels is more than 12 times higher than that of the traditional TCLs of 2 H 11/2 / 4 S 3/2 at subzero temperature. Therefore, it is expected to realize high-sensitivity temperature detection from subzero to elevated temperatures by combining two pairs of different TCLs. In addition, the potential of Er 3+ / Yb 3+ codoped BYO phosphors to be used as an optical heater is studied. The generated temperature can be accurately monitored by BYO:Er 3+ /Yb 3+ phosphors and regulated by adjusting the excitation power, which indicate that BYO:Er 3+ /Yb 3+ phosphors can be used as an optical heating device.