In conditions of depletion of mineral reserves, plant biomass is considered a renewable natural resource that can be photocatalytically processed to produce energy-intensive and environmentally friendly hydrogen fuel. In this regard, the present article focuses on the improvement of photocatalytic activity of the layered perovskite-structured niobate HCa₂Nb₃O₁₀ in the reactions of hydrogen production from aqueous solutions of typical plant biomass components, glucose and xylose, via its exfoliation into nanosheets followed by their reassembly and modification with a Pt cocatalyst. The reassembled compound obtained was shown to outperform in the activity the initial niobate and reference photocatalyst TiO₂ P25 Degussa up to 6.3 and 5.3 times, respectively, providing a hydrogen production rate up to 24.2 mmol h⁻¹g⁻¹ and apparent quantum efficiency up to 10% in the mid-near ultraviolet range.

The search for effective and reliable methods of photosensitization of oxide-based semiconductor materials is of great significance for their use in photocatalytic reactions of hydrogen production and environmental remediation under natural sunlight. The present study is focused on partial substitution of titanium with manganese in the structure of layered perovskite-like titanate Na₂La₂Ti₃O₁₀, which was employed to yield a series of photocatalytically active materials, Na₂La₂Mn_xTi_3−xO₁₀ (x = 0.002–1.0), as well as their protonated forms H₂La₂Mn_xTi_3−xO₁₀ and nanosheets. It was established that the manganese cations Mn⁴⁺ are embedded in the middle sublayer of oxygen octahedra in the perovskite slabs La₂Mn_xTi_3−xO₁₀²⁻ and that the maximum achievable manganese content x in the products is ≈0.9. The partial cationic substitution in the perovskite sublattice led to a pronounced contraction of the optical band gap from 3.20 to 1.35 eV (depending on x) and, therefore, allowed the corresponding photocatalysts to utilize not only ultraviolet, but also visible and near-infrared light with wavelengths up to ≈920 nm. The materials obtained were tested as photocatalysts of hydrogen evolution from aqueous methanol, and the greatest activity in this reaction was demonstrated by the samples with low manganese contents (x = 0.002–0.01). However, the materials with greater substitution degrees may be of high interest for use in other photocatalytic processes and, especially, in thermophotocatalysis due to their improved ability to absorb the near-infrared part of solar radiation.