氢氧分离式光电分解水

摘要：

太阳能产氢一直是人类孜孜追求的目标。但如何实现大规模持续、廉价产氢是为棘手又亟待解决的问题。在传统电解槽结构中，产氢和产氧在同一槽中。但这一方式在光电产氢领域受到了大的限制。如何整合太阳能的转化与电解水产氢成为关键。本文中，作者通过分离产氢、产氧过程，并利用辅助电作为“调节剂”，成功实现大面积太阳能转化与集中式产氢，太阳能产氢转换效率达到7.5 %。同时，较之传统光电化学体系，该方法在成本、安全性以及稳定性上都具有一定的竞争优势。

先来看看作者的构想图：

好和谐的一张图。地毯式的太阳能面板加集中式电解水产氢。

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.

传统电解水装置如下图1a、1b所示，产氢、产氧在同一装置中进行，利用离子交换膜或者盐桥实现连接。近期，人们提出了一种新型聚合物薄膜电解槽结构。其利用可溶性分子氧化还原调节剂（硅钨酸）实现产氢和产氧的分离，如下图1c所示。但其效率低下，且需要贵金属铂作为产氢催化剂。本文则采用固体氧化还原调节剂作为离子交换体系，实现氢氧分离，并可多次循环利用。至于材料的选择方法请参见原文。

图 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.

具体表征数据见下图2、3和表一：

图 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.

图 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，更多准确信息请移步原文。