An Exploration of the Four‐Decade‐Long History of Photocatalytic Water Treatment: Analysis of Key Advancements, Underlying Relationships, and Failures along the Way

Abstract

This study explores the decade‐long history of photocatalytic water treatment using a novel integration of the Delphi method and the preferred reporting items for systematic reviews and meta‐analyses approach, along with bibliometric analysis, to examine publication trends, author and country coauthorship networks, keyword co‐occurrence, citation analysis, and catalyst/contaminant evolution over time. The key findings include a steady increase in annual publications, a shift in dominant disciplines toward Environmental Sciences and Chemical Engineering, the role of specific authors in country productivity and citation rankings, and a growing need for international collaboration. TiO2‐ and TiO2‐based materials remain dominant, but a clear trend of abandonment in favor of novel materials is observed. Solar light is gaining importance for the photocatalytic elimination of aquatic pollutants, shifting simple organic compounds to priority substances. The evolution of this field is highlighted by tracing advancements in catalyst diversity and complexity, process optimization, and intensification. However, despite important milestone achievements, persistent knowledge gaps, discrepancies in comparability among studies, a lack of understanding of the fundamentals, and low funding incentives for transitioning to market hinder large‐scale applications. This study aims to provide a comprehensive guide for researchers by summarizing previous findings, unsuccessful approaches, and possibilities for improving photocatalytic applications.