Voc4Cat: A Sustainable Vocabulary Toolkit for FAIR Data Annotation in Catalysis and Beyond

The effective implementation of FAIR (Findable, Accessible, Interoperable, Reusable) data principles[1] in science requires the development of shared, standards-compliant, machine-readable vocabularies to unambiguously annotate data and metadata. In catalysis, the lack of such a domain-specific vocabulary motivated the development of Voc4Cat. Voc4Cat is a community-curated, SKOS-compliant, high technology readiness level (TRL: 8), catalysis-specific vocabulary. Voc4Cat provides a curated, persistent, and semantically pre-cise collection of domain-specific concepts, each assigned with a uniform resource identifier (URI), enabling unambiguous term resolution and integration across various applications. Ex-amples of current and future integrations of Voc4Cat include electronic lab notebooks (e.g., NOMAD, CaReD, LabIMotion), data repositories (e.g., Repo4Cat, CaRMen), educational tools (e.g, RDM4Lab), and a keyword catalogue in scientific publishing (e.g., ChemCatChem) thus serving a wide range of stakeholders. Voc4Cat prioritizes and welcomes community participation in its development, curation and in enriching its contents through the contribution of concepts and definitions. The vocabulary is openly accessible via its dedicated homepage and GitHub repository, and contributions are encouraged from users of all levels of expertise. Comprehensible and extensive documenta-tion, - including guidelines [2] (based on the ANSI/NISO Z39.19-2005 (R2010) standard [3]) and a step-by-step contribution guide [4] - ensures a consistent curation process and a low barrier of participation across all expertise levels. Contributions are submitted by editing the vocabu-lary excel file (.xlsx) with e.g., new concepts or definitions, and initiating a pull request via GitHub. An automated continuous integration (CI) pipeline validates submissions, which are subsequently reviewed by the curation team. This process enables timely integration of community input while maintaining the semantic consistency of the vocabulary. Voc4Cart is a scientific resource that is built with sustainability in mind. The guiding principles have recently been summarized as O3 guidelines,[5] stressing the importance of: - Open data: Voc4Cat is CC0-licenced, with its documentation being available under a CC-BY license. - Open tools: All maintenance tools are developed on GitHub under an open license, including the voc4cat-tool, voc4cat-template, and a Python Package. - Open infrastructure: Hosting and development rely solely on existing open services, such as the free GitHub or hosting code, documentation, and the vocabulary re-source, and the free w3id.org service for permanent URIs. While initially scoped for catalysis, the Voc4Cat toolkit is intentionally domain-agnostic and extensible and can be readily adapted for use in other scientific or technical disciplines seek-ing to build sustainable, community-driven semantic infrastructures.