Economical Pt-Free Catalysts for Counter Electrodes of Dye-Sensitized Solar Cells

Three classes (carbides, nitrides and oxides) of nanoscaled early-transition-metal catalysts have been proposed to replace the expensive Pt catalyst as counter electrodes (CEs) in dye-sensitized solar cells (DSCs). Of these catalysts, Cr₃C₂, CrN, VC­(N), VN, TiC, TiC­(N), TiN, and V₂O₃ all showed excellent catalytic activity for the reduction of I₃^– to I^– in the electrolyte. Further, VC embedded in mesoporous carbon (VC–MC) was prepared through in situ synthesis. The I₃^–/I^– DSC based on the VC–MC CE reached a high power conversion efficiency (PCE) of 7.63%, comparable to the photovoltaic performance of the DSC using a Pt CE (7.50%). In addition, the carbide catalysts demonstrated catalytic activity higher than that of Pt for the regeneration of a new organic redox couple of T₂/T^–. The T₂/T^– DSCs using TiC and VC–MC CEs showed PCEs of 4.96 and 5.15%, much higher than that of the DSC using a Pt CE (3.66%). This work expands the list of potential CE catalysts, which can help reduce the cost of DSCs and thereby encourage their fundamental research and commercial application

Spry2 suppresses ERK1/2 phosphorylation in human lens epithelial cells.

<p><b>(A-B)</b> Cultured human lens epithelial cells were transfected with Spry2 siRNA or Spry2 plasmid and treated with or without TGFβ for 48h. Untransfected cells, cells transfected with scrambled siRNA or empty vector were used as controls. Proteins were extracted and probed for pERK1/2 and total ERK1/2. β-actin was used as a loading control. <b>(C-D)</b> Quantification of the pERK1/2 and total ERK1/2 expression levels in A and B, respectively. Fold change relative to the level of untransfected groups is displayed. **<i>P</i><0.01, ***<i>P</i><0.001, n = 3.</p

EMT induced by Spry2 downregulation was inhibited by Smad and ERK1/2 specific inhibitors.

<p><b>(A)</b> Cultured human lens epithelial cells were transfected with scrambled siRNA or Spry2 siRNA and treated with Smad inhibitor SB431542 (10.0μM) or ERK1/2 inhibitor U1026 (10.0μM) or both for 24h. Proteins were extracted and probed for pSmad, total Smad, pERK1/2, total ERK1/2, α-SMA and Fn. β-actin was used as a loading control. <b>(B-D)</b> Quantification of the protein expression levels in A. Fold change relative to the level of the scrambled siRNA transfected group is displayed. *<i>P</i><0.05, **<i>P</i><0.01, ***<i>P</i><0.001, NS: not significant, n = 3.</p

A working model for Spry2 in regulation of TGFβ signaling pathway.

<p>TGFβ signals through canonical pathway and non-canonical pathway. The canonical pathway needs phosphorylation of Smad2, and can be blocked by SB431542. The non-canonical pathway needs phosphorylation of ERK1/2, and can be inhibited by U0126. Spry2 can block both canonical and non-canonical pathways, thus suppress TGFβ-induced EMT.</p

Spry2 inhibits TGFβ-induced EMT in human lens epithelial cells.

<p><b>(A)</b> Cultured human lens epithelial cells were transfected with Spry2 siRNA or Spry2 plasmid and treated with or without TGFβ for 48h. The mRNA levels of α-SMA, Fn and Vim were determined by real-time PCR and normalized to GAPDH. Fold change relative to the level of the untransfected groups is displayed. **<i>P</i><0.01, ***<i>P</i><0.001, n = 3 <b>(B)</b> Cells were transfected with Spry2 siRNA or Spry2 plasmid and treated with or without TGFβ for 48h. Immunofluorescence was performed by probing Spry2, Fn, Col I, Col IV and DAPI. Scale bar: 50μm <b>(C-D)</b> Cells were transfected with Spry2 siRNA or Spry2 plasmid and treated with or without TGFβ for 48h. Untransfected cells, cells transfected with scrambled siRNA or empty vector were used as controls. Proteins were extracted and probed for Spry2, α-SMA, Fn, Col IV. β-actin was used as a loading control. <b>(E-F)</b> Quantification of the protein expression levels in C and D, respectively. Fold change relative to the level of the untransfected groups is displayed. *<i>P</i><0.05, **<i>P</i><0.01, ***<i>P</i><0.001, NS: not significant, n = 3.</p

Primers used for real-time quantitative PCR.

<p>Primers used for real-time quantitative PCR.</p

Spry2 expression level is decreased in anterior capsule LECs of ASC patients.

<p>(<b>A</b>) Representative slit-lamp microscope photo of an ASC patient (60 years old, Female). The white arrow indicates the irregular fibrotic opacity beneath the anterior capsule. (<b>B</b>) Total RNA was extracted from the anterior capsules of ASC patients, age-matched cortical cataract patients and postmortem human lens (control). The mRNA level of Spry2 was determined using real-time PCR and normalized to GAPDH. ***<i>P</i><0.001, NS: not significant, n = 6. Fold change relative to the level of the control groups is displayed. (<b>C</b>) Lens anterior capsule whole-mounts from ASC patients, age-matched cortical cataract patients, and postmortem human lens (control) were probed for Spry2 (green), α-SMA (red) and DAPI (blue). Images were acquired from the central area of each sample. Scale bar: 10μm.</p