Photocatalysts Based on Graphite-like Carbon Nitride with a Low Content of Rhodium and Palladium for Hydrogen Production under Visible Light

In this study, we proposed photocatalysts based on graphite-like carbon nitride with a low content (0.01–0.5 wt.%) of noble metals (Pd, Rh) for hydrogen evolution under visible light irradiation. As precursors of rhodium and palladium, labile aqua and nitrato complexes [Rh(2)(H(2)O)(8)(μ-OH)(2)](NO(3))(4)∙4H(2)O and (Et(4)N)(2)[Pd(NO(3))(4)], respectively, were proposed. To obtain metallic particles, reduction was carried out in H(2) at 400 °C. The synthesized photocatalysts were studied using X-ray diffraction, X-ray photoelectron spectroscopy, UV–Vis diffuse reflectance spectroscopy and high-resolution transmission electron microscopy. The activity of the photocatalysts was tested in the hydrogen evolution from aqueous and aqueous alkaline solutions of TEOA under visible light with a wavelength of 428 nm. It was shown that the activity for the 0.01–0.5% Rh/g-C(3)N(4) series is higher than in the case of the 0.01–0.5% Pd/g-C(3)N(4) photocatalysts. The 0.5% Rh/g-C(3)N(4) sample showed the highest activity per gram of catalyst, equal to 3.9 mmol g(cat)(–1) h(–1), whereas the most efficient use of the metal particles was found over the 0.1% Rh/g-C(3)N(4) photocatalyst, with the activity of 2.4 mol per gram of Rh per hour. The data obtained are of interest and can serve for further research in the field of photocatalytic hydrogen evolution using noble metals as cocatalysts.