Highly efficient hydrogen production under visible light over g-C3N4-based photocatalysts with low platinum content

Abstract

The successive combination including thermolysis of melamine cyanurate complex, chemisorption of platinum from the solution of the labile nitratocomplex and, finally, reductive treatment with hydrogen was implemented to obtain highly active Pt/g-C3N4 photocatalysts (0.01–0.5 wt% of Pt). The prepared in this way materials evinces photocatalytic activity in hydrogen evolution reaction from TEOA/water solutions with the superb rate of H2 evolution per platinum atom loaded (1560 h−1) and the net rates being among the highest reported to date values (11 mmol·g−1·h−1). Such a remarkable performance correlates with the structure of these materials where the branchy net of the pores provides easy access of reagents to and ejection of products from the nanoparticulated Pt co-catalysts. A crucial contribution to the formation of the noted Pt/g-C3N4 morphology ascribed to the self-catalyzed hydrogenation of the Pt/g-C3N4 composites resulting in “scarifying” of the g-C3N4 particles preferentially at the surface layer where Pt species are located. Taking into account the high productivity of the synthesized Pt/C3N4 materials and robustness of the preparation method this approach can be convenient for the large-scale applications that were successfully demonstrated under pilot installation (total volume 1 l) with the fuel cell (PEMFC with max output 1 W) as a hydrogen consumer. Evaluation of the productivity of the large-scale reactor for hydrogen production with a scaled-up installation was carried out. This study also grants a new vision on developing expandable synthetic approaches to enhance the performance of carbon nitride-based photocatalysts and at the same time mitigate the noble metal co-catalysts usage.