Figure
6 . (a) Comparison of hydrogen evolution of CuP, CoP and Cu-Cu-2P-2
catalyst samples; (b) Comparison of hydrogen production activities of
catalysts with different phosphating degrees; (c) Comparison of hydrogen
production activities of different Cu-MOFs catalysts; (d) Effect of
triethanolamine aqueous solution with different pH on the photocatalytic
activity of Cu-Co-2P-2.
The cyclic stability of photocatalysts is very important for their
applications. As shown in Figure 7, there is Cu-Co-2P-2 composite
photocatalytic activity test comparison for four cycles in consecutive
20 h. The catalyst and sacrificial reagent were not re-added during the
entire experiment. 10 mg of EY is added to the reaction flask again at
each regassing. Stability tests show that the total amount of produced
hydrogen is only slightly reduced at the end of each cycle. This is
mainly because the adsorbed EY dye is easily desorbed and diffused into
the solution, and the catalyst has slight photo-induced corrosion [38,
40, 41]. Compared with the first cycle, the fourth cycle is only down
by 13.7%, which indicates that the Cu-Co-2P-2 photocatalyst has
excellent cycle stability and certain application prospects.