The TiO2|Pt system presents the best performing photocatalyst under UV-vis irradiation, whereas the precious metal-free CNx|Ni2P allows visible-light operation, albeit at lower efficiency due to limitations from light absorption, co-catalyst leaching , oxidative power/kinetics and the pH-dependent activity of the co-catalyst. For example, the Ni2P is known to perform well as a co-catalyst under alkaline conditions (pH>13) by forming a thin Ni(OH)2 layer facilitating water dissociation, but is less active in neutral pH. From an economics and sustainability perspective, strongly alkaline solutions are not desirable. Although the use of Pt in the case of TiO2 (which is chemically robust, non-toxic and relatively inexpensive) may be considered as a bottleneck for practical applications, we note that the amount of Pt loaded is only 1% and may be sourced from discarded electronic waste materials or other sectors in future and can be reused. The H2 evolution activities and yields obtained by our systems using milder enzymaticpre-treatment of PCL and PET plastics exceed the values reported for most representative heterogenous photocatalyst systems/processes employing harsh pre-treatment conditions as discussed in Table .