Efficient Photocatalytic Hydrogen Production over NiS-Modified Cadmium and Manganese Sulfide Solid Solutions.

In this work, new photocatalysts based on Cd 1-x Mn x S sulfide solid solutions were synthesized by varying the fraction of MnS (x = 0.4, 0.6, and 0.8) and the hydrothermal treatment temperature (T = 100, 120, 140, and 160 °C). The active samples were modified with Pt and NiS co-catalysts. Characterization was performed using various methods, including XRD, XPS, HR TEM, and UV-vis spectroscopy. The photocatalytic activity was tested in hydrogen evolution from aqueous solutions of Na 2 S/Na 2 SO 3 and glucose under visible light (425 nm). When studying the process of hydrogen evolution using an equimolar mixture of Na 2 S/Na 2 SO 3 as a sacrificial agent, the photocatalysts Cd 0.5 Mn 0.5 S/Mn(OH) 2 (T = 120 °C) and Cd 0.4 Mn 0.6 S (T = 160 °C) demonstrated the highest activity among the non-modified solid solutions. The deposition of NiS co-catalyst led to a significant increase in activity. The best activity in the case of the modified samples was shown by 0.5 wt.% NiS/Cd 0.5 Mn 0.5 S (T = 120 °C) at the extraordinary level of 34.2 mmol g -1 h -1 (AQE 14.4%) for the Na 2 S/Na 2 SO 3 solution and 4.6 mmol g -1 h -1 (AQE 2.9%) for the glucose solution. The nickel-containing samples possessed a high stability in solutions of both sodium sulfide/sulfite and glucose. Thus, nickel sulfide is considered an alternative to depositing precious metals, which is attractive from an economic point of view. It worth noting that the process of photocatalytic hydrogen evolution from sugar solutions by adding samples based on Cd 1-x Mn x S has not been studied before.