Vacancies enhance proton conductivity Proton-exchange membranes (PEMs) allow for the transport of protons while acting as electrical insulators and ensuring that reactants are kept apart; therefore, they are a key component in devices such as low-temperature fuel cells. PEMs are typically made from polymers or materials embedded in a polymer matrix and need to operate in conditions of very high humidity. Starting with an inorganic, layered material, CdPS3, Qian et al. show that the removal of a small amount of cadmium introduces vacancies that greatly increase the proton conductivity of the PEMs (see the Perspective by Wang and He). The process works for manganese-based membranes as well, and high lithium ion transport was also observed. Science, this issue p. 596; see also p. 525 Cd vacancies in a layered Cd0.85PS3Li0.15H0.15 membrane enable excellent proton conductivity. Proton transport in nanochannels under humid conditions is crucial for the application in energy storage and conversion. However, existing materials, including Nafion, suffer from limited conductivity of up to 0.2 siemens per centimeter. We report a class of membranes assembled with two-dimensional transition-metal phosphorus trichalcogenide nanosheets, in which the transition-metal vacancies enable exceptionally high ion conductivity. A Cd0.85PS3Li0.15H0.15 membrane exhibits a proton conduction dominant conductivity of ~0.95 siemens per centimeter at 90° Celsius and 98% relative humidity. This performance mainly originates from the abundant proton donor centers, easy proton desorption, and excellent hydration of the membranes induced by cadmium vacancies. We also observed superhigh lithium ion conductivity in Cd0.85PS3Li0.3 and Mn0.77PS3Li0.46 membranes.

中文翻译：

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由 Cd 空位实现的具有高质子传导性的 CdPS3 纳米片基膜

空位增强质子传导性 质子交换膜 (PEM) 允许传输质子，同时充当电绝缘体并确保反应物分开；因此，它们是低温燃料电池等设备的关键部件。PEM 通常由聚合物或嵌入聚合物基质中的材料制成，需要在非常高的湿度条件下运行。从无机层状材料 CdPS3 开始，Qian 等人。表明去除少量镉会引入空位，从而大大增加 PEM 的质子传导率（参见 Wang 和 He 的观点）。该过程也适用于锰基膜，并且还观察到高锂离子传输。科学，这个问题 p。596; 另见第 层状 Cd0.85PS3Li0.15H0 中有 525 个 Cd 空位。15 膜具有出色的质子传导性。潮湿条件下纳米通道中的质子传输对于能量存储和转换中的应用至关重要。然而，包括 Nafion 在内的现有材料的电导率有限，每厘米最高可达 0.2 西门子。我们报告了一类由二维过渡金属三硫族化合物磷纳米片组装而成的膜，其中过渡金属空位可实现极高的离子电导率。Cd0.85PS3Li0.15H0.15 膜在 90°C 和 98% 相对湿度下表现出约 0.95 西门子/厘米的质子传导主导电导率。这种性能主要源于丰富的质子供体中心、容易的质子解吸以及镉空位引起的膜良好的水合作用。