MXenes exhibit exceptional versatility, enabling applications ranging from energy storage, catalysis, sensing, water purification, electromagnetic shielding. Particularly, even MXenes are materials that can be enginered from their MAX phase composition to become structurally adaptable precursors. The ability to finely tune composition and precursor incorporated dopants in a nanoscale topology opens a potential path toward engineered heterostructures capable of supporting magneto‑excitonic interactions [1]. 

An example of this transformation is spontaneous oxidation of MXenes in aqueous dispersions, typically regarded as a degradation pathway, which can instead be seen as a versatile synthetic route for producing TiO₂ composites with tunable structural and electronic properties [2]. In this work, we investigate the controlled transformation of Ti₃C₂Tₓ MXene into carbon implemented titanium oxide nanostructures and demonstrate how the resulting evolution in morphology, band structure, and defect formation directly influences photocatalytic hydrogen generation in heterogeneous solid-gas conditions. Composites derived from highly oxidized “white” MXene solutions exhibit significantly improved semiconductor quality, evidenced by a reduction in Urbach energies and deliver markedly enhanced photocatalytic performance. 

Overall, the presented work show how the controlled oxidation of Ti₃C₂Tₓ MXene provides a simple yet powerful route to tailor TiO₂ semiconductor quality and photocatalytic response. Paving the way to produce Titanium MXene‑derived oxides as efficient Hydrogen photocatalysts and the begining of defect‑engineered MXene precursors that may produce more complex materials and enable more complex light‑matter interactions.

[1] Li, Y.; Wang, Z.; Wang, Y.; Kovács, A.; Foo, C.; Dunin‑Borkowski, R. E.; Lu, Y.; Taylor, R. A.; Wu, C.; Tsang, S. C. E.
Local magnetic spin mismatch promoting photocatalytic overall water splitting with exceptional solar‑to‑hydrogen efficiency.
Energy & Environmental Science, 2022, 15, 265–276. DOI: 10.1039/d1ee02222a.

[2] Sunderiya, S.; Suragtkhuu, S.; Purevdorj, S.; Ochirkhuyag, T.; Bat‑Erdene, M.; Myagmarsereejid, P.; Slattery, A. D.; Bati, A. S. R.; Shapter, J. G.; Odkhuu, D.; Davaasambuu, S.; Batmunkh, M. Understanding the oxidation chemistry of Ti₃C₂Tₓ (MXene) sheets and their catalytic performances. Journal of Energy Chemistry, 2024. DOI: 10.1016/j.jechem.2023.09.037.