Solar water splitting into H2 and O2 is a promising approach to provide renewable fuels. However, the presence of O2 hampers H2 generation and most photocatalysts show a major drop...

The feasibility of a solar-driven photoelectrochemical process to generate hydrogen fuel from metal mine polluted water while simultaneously recovering heavy metals has been explored.

This work showcases the performance of [NiFeSe] hydrogenase from Desulfomicrobium baculatum for solar‐driven hydrogen generation in a variety of organic‐based deep eutectic solvents. Despite its well‐known sensitivity towards air and organic solvents, the hydrogenase shows remarkable performance under an aerobic atmosphere in these solvents when paired with a TiO2 photocatalyst. Tuning the water content further increases hydrogen evolution activity to a TOF of 60±3 s−1 and quantum yield to 2.3±0.4 % under aerobic conditions, compared to a TOF of 4 s−1 in a purely aqueous solvent. Contrary to common belief, this work therefore demonstrates that placing natural hydrogenases into non‐natural environments can enhance their intrinsic activity beyond their natural performance, paving the way for full water splitting using hydrogenases.

This work demonstrates a two-step gram-scale synthesis of presynthesized silver (Ag) nanoparticles impregnated with mesoporous TiO 2 and evaluates their feasibility for wastewater treatment and hydrogen gas generation under natural sunlight. Paracetamol was chosen as the model pharmaceutical pollutant for evaluating photocatalytic performance. A systematic material analysis (morphology, chemical environment, optical bandgap energy) of the Ag/TiO 2 photocatalyst powder was carried out, and the influence of material properties on the performance is discussed in detail. The experimental results showed that the decoration of anatase TiO 2 nanoparticles (size between 80 and 100 nm) with 5 nm Ag nanoparticles (1 wt %) induced visible-light absorption and enhanced charge carrier separation. As a result, 0.01 g/L Ag/TiO 2 effectively removed 99% of 0.01 g/L paracetamol in 120 min and exhibited 60% higher photocatalytic removal than pristine TiO 2 . Alongside paracetamol degradation, Ag/TiO 2 led to the generation of 1729 μmol H 2 g −1 h −1 . This proof-of-concept approach for tandem pollutant degradation and hydrogen generation was further evaluated with rare earth metal (lanthanum)-and nonmetal (nitrogen)-doped TiO 2 , which also showed a positive response. Using a combination of ab initio calculations and our new theory model, we revealed that the enhanced photocatalytic performance of Ag/TiO 2 was due to the surface Fermi-level change of TiO 2 and lowered surface reaction energy barrier for water pollutant oxidation. This work opens new opportunities for exploiting tandem photocatalytic routes beyond water splitting and understanding the simultaneous reactions in metal-doped metal oxide photocatalyst systems under natural sunlight.

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