To strengthen the adhesion of platinum layer to counterelectrodes of dye sensitized solar cells, titanium thin film has been utilized as adhesion layer between platinum and substrate [Wei et al., Appl. Phys. Lett. 90, 153122 (2007)]. In our study, platinum/titanium bilayer counterelectrodes were fabricated by magnetron sputtering. The structural, electrical, and electrochemical properties of the bilayer counterelectrode were studied by varying the thickness of both platinum and titanium layers. The influence of both electrochemical active surface and crystallite size on charge transfer resistance of the bilayer counterelectrode was explored. From these evaluations, it was found that the as-prepared titanium layer was almost amorphous, and intermetallic phase was formed between platinum and titanium layers. As expected, sheet resistance of the electrode decreased with the increase in deposition time of both platinum and titanium layers. Metal titanium was found to be inert in the catalyzing reduction in tri-iodide. With the increment of deposition time of platinum layers, charge transfer resistance of the electrode decreased quickly first, and then reached a plateau after which it changed slightly. This outcome differs from that reported before. Careful examination showed that such a behavior was related closely to the electrochemical active surface area of electrode and platinum crystallite size. For a given electrolyte, charge transfer resistance decreased with the increase in electrochemical active surface and increased with the increment of the latter. Thus, a competition was observed between the two factors, which supports the suggestion of former researchers.

Under the dual pressures of climate change and urbanization, cities in China are experiencing increasingly severe flooding. Using the Yushan Lake area in Ma’anshan City, Anhui Province, as a case study, we employed the InfoWorks Integrated Catchment Management (ICM) hydraulic model to analyze the drainage and flood prevention system of the region and assess the current infrastructure for drainage and flood control. There are 117 pipelines with a return period lower than one year for stormwater and combined sewer systems, accounting for 12.3% of the total number of pipelines. The number of pipelines meeting the one-year but not the three-year return period standard is 700, representing 70.2%. Only 17.5% of the pipelines are capable of handling events exceeding the one-year standard. In simulating a 24 h, 30-year return period rainfall event, the results indicate that floodwater accumulation in the study area is predominantly between 0.15 m and 0.3 m. Most risk areas are classified as low risk, covering an area of 36.398 hectares, followed by medium and high-risk areas, which cover 8.226 hectares and 3.087 hectares, respectively. The Ma’anshan Yushan Lake area has, overall, certain flood control capabilities but faces flood risks during storms with return periods exceeding three years. This research offers valuable insights for improving urban flood management in Ma’anshan City through the development of a stormwater management model for the Yushan Lake area.

Both the renovation of rainwater pipes and the addition of sponge city facilities in the low-terrain residences of urban fringes were rarely systematically simulated using the Storm Water Management Model (SWMM). With the waterlogging prevention project in an old residential quarter at a fringe of Hefei city being an example, this study used the SWMM to simulate the effect of the renovation of rainwater pipes and sponge city facilities under different return periods. The results showed the key nodes on the main pipes met the drainage requirements based on water depth analysis after renovation below the 20-year return period, and the reduction rate of the maximum water depth at the key node J5 was the greatest, with 87.7%. The four flow parameters (the average flow rate, the peak flow rate, the total discharge, and the percentage of water flow frequency) for the two outlets (PFK1 and PFK2) all improved after renovation under five return periods (2, 5, 10, 20, and 50 years [a]). The addition of sponge city facilities effectively reduced the amount of rainwater runoff from 28.68% to 14.78% during 2 a to 50 a, and the maximum reduction rate of water depth, being 61.15%, appeared in J5 under 20 a. The curve integral area of the depth over the elapsed time was innovatively used to indirectly express the accumulated rainwater volume through the rainwater well. This study verified that the SWMM model can be well applied to old low-terrain residential quarters in urban fringes and broadened the application scenario of the model.