Pitfalls in the characterisation of the hydrogen sorption properties of materials

Characterising the hydrogen sorption properties of materials is important for a range of applications, including solid state hydrogen storage, electrochemical and thermal energy storage using metal hydrides, and H2 gas compression and purification. However, it can be technically demanding and subject to significant error if not performed with care. In this article, potential pitfalls in the performance of hydrogen sorption measurements are discussed. The topics covered include instrument design and calibration, sample size choice, sample and gas purity, isotherm measurement procedure and issues associated with data reduction. Approaches to validating equipment and isotherm measurements are also discussed. Different sample types are considered, including metal and complex hydrides and nanoporous adsorbents, such as porous carbons, zeolites and metal-organic frameworks (MOFs).