氫氧分離式光電分解水

摘要：

太陽(yáng)能產(chǎn)氫一直是人類孜孜追求的目標(biāo)。但如何實(shí)現(xiàn)大規(guī)模持續(xù)、廉價(jià)產(chǎn)氫是為棘手又亟待解決的問題。在傳統(tǒng)電解槽結(jié)構(gòu)中，產(chǎn)氫和產(chǎn)氧在同一槽中。但這一方式在光電產(chǎn)氫領(lǐng)域受到了大的限制。如何整合太陽(yáng)能的轉(zhuǎn)化與電解水產(chǎn)氫成為關(guān)鍵。本文中，作者通過分離產(chǎn)氫、產(chǎn)氧過程，并利用輔助電作為“調(diào)節(jié)劑”，成功實(shí)現(xiàn)大面積太陽(yáng)能轉(zhuǎn)化與集中式產(chǎn)氫，太陽(yáng)能產(chǎn)氫轉(zhuǎn)換效率達(dá)到7.5 %。同時(shí)，較之傳統(tǒng)光電化學(xué)體系，該方法在成本、安全性以及穩(wěn)定性上都具有一定的競(jìng)爭(zhēng)優(yōu)勢(shì)。

先來看看作者的構(gòu)想圖：

好和諧的一張圖。地毯式的太陽(yáng)能面板加集中式電解水產(chǎn)氫。

Conceptual illustration of a solar hydrogen refuelling station with distributed PEC solar cells producing O2 and a centralized H2 generator.A detailed conceptual design of the solar field is illustrated in Supplementary Fig. 26.

傳統(tǒng)電解水裝置如下圖1a、1b所示，產(chǎn)氫、產(chǎn)氧在同一裝置中進(jìn)行，利用離子交換膜或者鹽橋?qū)崿F(xiàn)連接。近期，人們提出了一種新型聚合物薄膜電解槽結(jié)構(gòu)。其利用可溶性分子氧化還原調(diào)節(jié)劑（硅鎢酸）實(shí)現(xiàn)產(chǎn)氫和產(chǎn)氧的分離，如下圖1c所示。但其效率低下，且需要貴金屬鉑作為產(chǎn)氫催化劑。本文則采用固體氧化還原調(diào)節(jié)劑作為離子交換體系，實(shí)現(xiàn)氫氧分離，并可多次循環(huán)利用。至于材料的選擇方法請(qǐng)參見原文。

圖 1

Figure 1 | Water electrolysis cell architectures. a, Conventional configuration of an alkaline water electrolysis cell. b, The same as in a with the membrane replaced by a salt bridge. c, The new PEM electrolyser configuration proposed in ref. 6 with a soluble redox mediator that enables decoupling the H2 and O2generation steps. d, Our membrane-free configuration for alkaline water electrolysis in separate hydrogen and oxygen cells8. The anode can be replaced by a photoanode or a photoanode–photovoltaic tandem stack, thus turning the electrolysis cell into a PEC water splitting solar cell that directly convert water and solar power to hydrogen fuel.

具體表征數(shù)據(jù)見下圖2、3和表一：

圖 2

Figure 2 | Two-cell water electrolysis cycles in separate hydrogen and oxygen cells. a, Vappl as a function of time during 20 h of operation at a constant current of 45 mA (5 mA cm−2 ). b, The cycle duration plotted against the cycle number. The measurement was carried out in 1 M NaOH alkaline aqueous solution at ambient temperature.

圖 3

Figure 3 | Solar water splitting system with separate oxygen and hydrogen cells. Current density–voltage (J–V) characteristics of the individual components, the PV module (red curve) and water electrolysis system (blue curve), and the operation points of the coupled PV–electrolysis system (green dots). The red X marks the maximum power point of the PV module. The black dashed line curve shows the J–V characteristics of a PV module of the same model based on the vendor’s specifications. The inset shows a schematic illustration of the system.

表一

水平有限，更多準(zhǔn)確信息請(qǐng)移步原文。