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【Objective】 Hydraulic hammer is a common phenomenon, and the purpose of this paper is to study the effect of air valve on hydraulic transient and water hammer protection of multi-source and high-lift water supply project when the pumps were losing power. 【Method】 The model of water supply system was established using the one-dimensional hydraulic transients and the method of characteristic (MOC); Free gas cavitation theory was used to describe the air valve. Quick-closing check valves were installed on the outlet of the pump and at the end of the ground section of the water lift pipe, respectively. Air valves are set at the high points of the water supply pipeline based on the calculated transition process under power-off conditions without any protective measures. The sensitivity of the air valve to different parameters was analyzed. 【Result】 In the absence of any protection measures, there was a large pressure drop at the outlet of the pump; the lowest water pressure in the water supply pipeline exceeded the standard value. After adding the protection device, the pump has no reversal; the minimum pressure behind the pump was more than -5 m, the minimum pressure of the water lift pipe behind the pump was more than -5 m, the maximum pressure of the water supply main pipe was lower than 160 m, and the minimum pressure was higher than -5 m. 【Conclusion】 The air valve has a good impact on controlling the negative pressure in both outlet of the water pump and the water supply pipeline. Our results have an implication for the design of water supply pumps for hydraulic projects.

The ever-growing over-consumption of fossil fuels and the accompanying massive emissions of CO2 have caused a severe energy crisis and environmental issues. Photoelectrochemical (PEC) reduction of CO2 that can combine and optimize the merits of both photocatalysis and electrocatalysis has been considered as an attractive prospect for addressing the two problems. Herein, photocathode materials are cores of PEC CO2 reduction. Among various photocathodes, Cu-based photocathodes attract much attention due to their low toxicity, low cost, earth-abundant properties, appropriate range of bandgap values and favorable band edges for CO2 reduction. More to the point, Cu-based photocathodes possess unique advantages for hydrocarbon production such as CO, HCOOH, CH4 or, more importantly, C2 products (like C2H4, C2H5OH and C2H6) compared with other metallic-based photoelectrodes. An insight into the relationships between the properties and functions of photocathodes plays a vital role in the field of PEC CO2 reduction. This review presents the development of Cu-based photocathode materials and discusses future research directions. The photocathode systems mainly include Cu-based oxides, Cu-based chalcogenides and Cu-based electrocatalyst coupled photocathodes. Subsequently, the existing major advantages and disadvantages of each system are also discussed. In conclusion, combining our analyses of the reported photocathodes, we will offer future challenges for the rational design of photoelectrodes. Overall, this review will present a significant overview of Cu-based photocathodes for PEC reduction of CO2. [ABSTRACT FROM AUTHOR]

α-SnWO 4 is a promising semiconductor for solar water splitting, however, its performance is limited by weak water oxidation and poor charge transfer. In this study, we employ a vapor deposition method to uniformly implement a carbon layer onto the surface of SnWO 4 coupled with a CoNiP cocatalyst, successfully constructing the integrated CoNiP/C/SnWO 4 film photoanode and alleviating the oxidation of Sn 2+ when loading electrocatalyst. Incorporating the carbon layer enhances the interface charge conduction behavior between the SnWO 4 substrate and the CoNiP cocatalyst, thereby mitigating charge recombination. The synergistic interplay between the carbon layer and CoNiP leads to a remarkable achievement, as evidenced by the photocurrent of 1.72 mA cm -2 (1.23 V vs. RHE) observed for SnWO 4 film measured in 0.2 M potassium phosphate buffer solution. In this work, we demonstrate the viability of tailoring SnWO 4 photoanode and provide valuable insights for prospective advancements in modifying SnWO 4 photoanode., (© 2024 Wiley-VCH GmbH.)

The low solubility of CO 2 molecules and the competition of the hydrogen evolution reaction (HER) in aqueous electrolytes pose significant challenges to the current photoelectrochemical (PEC) CO 2 reduction reaction. In this study, inspired by the bilayer phospholipid molecular structure of cell membranes, we developed a Cu 2 O/Sn photocathode that was modified with the bilayer surfactant DHAB for achieving high CO 2 permeability and suppressed HER. The Cu 2 O/Sn/DHAB photocathode stabilizes the *OCHO intermediate and facilitates the production of HCOOH. Our findings show that the Faradaic efficiency (FE) of HCOOH by the Cu 2 O/Sn/DHAB photoelectrode is 83.3%, significantly higher than that achieved with the Cu 2 O photoelectrode (FE HCOOH = 30.1%). Furthermore, the FE H2 produced by the Cu 2 O/Sn/DHAB photoelectrode is only 2.95% at -0.6 V vs RHE. The generation rate of HCOOH by the Cu 2 O/Sn/DHAB photoelectrode reaches 1.52 mmol·cm -2 ·h -1 ·L -1 at -0.7 V vs RHE. Our study provides a novel approach for the design of efficient photocathodes for CO 2 reduction.

The limited mass transfer of CO 2 and the competitive hydrogen evolution reaction (HER) during photoelectrochemical (PEC) CO 2 reduction usually result in low CO 2 reduction activity. Here, we constructed a Cu 2 O/Sn/PTFE photocathode with a hydrophobic surface based on Cu 2 O by physical vapor deposition and a dipping method. The CO faradaic efficiency (FE) increased from 34.5% (Cu 2 O) to 95.1% (Cu 2 O/Sn/PTFE) at -0.7 V vs. RHE, and the FE H2 decreased from 27.9% (Cu 2 O) to 3.8% (Cu 2 O/Sn/PTFE). The introduction of the hydrophobic layer enhances the local CO 2 concentration on the electrode surface and effectively isolates H + from the aqueous electrolyte, thereby enhancing the CO 2 reduction activity.