Formaldehyde and its surrogates as a C1 platform for defossilised modern societies.

This tutorial serves as an accessible introduction for researchers and students interested in the multifaceted chemistry of formaldehyde and its potential in shaping a more sustainable future. We explore its roles in renewable energy storage in the form of liquid organic hydrogen carriers (LOHCs) and renewable fuels, as well as carbon capture, utilization and storage (CCUS), and biomass valorisation. Furthermore, the relevance of these applications to several United Nations Sustainable Development Goals (UNSDGs 6, 7, 9, 12, and 13) is examined. Beyond the energy and environmental aspects, we discuss the use of formaldehyde and related surrogates in synthetic chemistry, focusing on innovative catalytic strategies to make use of this versatile and abundant C1 building block. Given formaldehyde's central role as an intermediate in both synthetic and biological C1-H2 reaction networks, the tutorial additionally offers discussion points on related small molecules, including methane, methanol, formic acid, CO, and CO2.