Reframing the GO–TiO2 paradigm: a critical review of core parameters for next-generation photocatalysts

The engineering of hybrid nanomaterials that synergistically couple adsorption and photocatalysis represents a transformative frontier in water remediation. Graphene oxide–titanium dioxide (GO–TiO 2 ) hybrids have emerged as the archetypal platform for this goal. However, despite a decade of intense research, progress has often been hampered by empirical trial‒and‒error approaches that obscure fundamental design principles, particularly in the active engineering of the interface for adsorption and reactivity, where structure–property–performance relationships remain poorly understood. In this mini-review, the multifaceted performance of GO–TiO 2 hybrids is deconstructed, and a rational design framework is proposed based on three pivotal descriptors: the oxidation degree of GO, the intrinsic electronic structure of the individual components, and the compositional ratio. While these descriptors may not be interdependent in a strict sense, it is contended that their combination exerts a decisive influence on the efficiency and characteristics of the final hybrid material. The literature is critically interrogated through this lens, revealing persistent mechanistic ambiguities—including conflicting reports on bandgap modulation—and reframing the role of adsorption from a passive prelude to an active modulator of interfacial kinetics, demanding advanced surface engineering strategies to actively tune its affinity and selectivity. It is contended that the resolution of these foundational inconsistencies in the binary model is an essential prerequisite for the successful advancement of the field towards more complex ternary and quaternary architectures. By establishing this fundamental design workflow grounded in interfacial descriptors, a paradigm shift is advocated towards rationally designed, multi-component photocatalysts, thereby paving the way for the next generation of sustainable water treatment technologies.