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Constructing a high‐quality interface with strong coupling interaction is highly desirable in composite photocatalysts for the efficient interfacial charge transfer. Herein, we prepared black phosphorus quantum dots/CdS (BPQDs/CdS) binary composites with tight interfacial contact via a facile electrostatic self‐assembly approach for efficient photocatalytic H2 evolution. The optimized H2 evolution rate of 3 wt % BPQDs/CdS can reach up to 9.9 mmol g−1 h−1 in lactic acid aqueous solution, 99 and 5.5 times greater than that of pristine BPQDs and CdS, respectively. Benefiting from the strong interface interaction between CdS and BPQDs in well‐contacted BPQDs/CdS composites, efficient charge separation can be achieved, leading to enhanced photocatalytic H2 evolution activity. Notably, the rapid transfer of photogenerated electrons from CdS to BPQDs was unambiguously confirmed by time‐resolved transient absorption spectroscopy. [ABSTRACT FROM AUTHOR]

Loading metal cocatalyst on semiconductor nanoparticles is a general strategy to enhance photocatalytic efficiency, while the consensus of selecting metal cocatalyst matching with semiconductor is still unclear. Herein, we investigated the charge transfer and separation efficiency between ZnO and cocatalysts Ag, Au, and Pt nanoparticles respectively using ultrafast mid‐IR transient absorption spectroscopy. We found that Ohmic contact of Ag with ZnO favoring electron transfer and charge separation, while Schottky junction of Pt or Au with ZnO preventing electron transfer from ZnO to metal. Thus Ohmic contact would be better than Schottky contact. Since photocatalytic efficiency is also determined by chemical catalytic efficiency, we proposed a dual metal cocatalyst strategy for improving the overall photocatalytic efficiency, with the inner metal forming Ohmic contact for efficient charge separation and shuttling electrons and the outer‐layer metal cocatalyst for optimizing the chemical reactivity. [ABSTRACT FROM AUTHOR]

[Display omitted] • A-site fluorinated D-A polymer PxF-T hybridized CdS photocatalyst are prepared. • Photocatalytic activity of the hybrid catalyst has been enhanced by ca. 30 times. • Carrier lifetimes in hybrid catalyst has been prolonged over 200 ps. • D-A polarity shows direct impact on photocatalytic performance. • Trade-off effect of fluorination on D-A polarity is discovered. Conventional inorganic semiconducting photocatalysts are facing insufficient light harvesting as well as severe charge recombination problems. Constructing heterostructures is a well-known strategy for accelerating charge separation, especially when hybridizing with donor–acceptor (D-A) conjugated polymers, which features tunable bandgap and high absorption coefficient, these problems can be simultaneously eased. However, the singlet exciton binding energy of D-A polymers is too high for efficient exciton dissociation. In this work, we designed fluorine substituted D-A polymer PxF-T (x = 1, 2, 4) and studied polarity effect on the interfacial charge transfer in CdS/PxF-T. By adjusting the numbers of F substitutions in the acceptor unit, the electron-withdrawing ability of A site can be improved while the polarity of the whole organic molecules is tuned. Among 1, 2, 4 substitutions, the photocatalytic hydrogen production results show that the single F substitution induces the most efficient hydrogen production activity of 6327.7 μmol·g−1·h−1, which is 30.1 times higher than that of pristine CdS. In addition, electrochemical test and time-resolved transient absorption study further confirmed the improved charge transfer activity. Density functional theory calculations reveal that the F introduction induced polarity change is responsible for the improved interfacial charge transfer efficiency, however the increased number of substitutions is not necessarily favorable for improved polarity. This work uncovers the effect of fluorine substitution on the intramolecular polarity of D-A semiconductor for the fabrication of efficient hybrid photocatalysts. [ABSTRACT FROM AUTHOR]

While the majority of the photochemical states and pathways related to the biological capture of solar energy are now well understood and provide paradigms for artificial device design, additional low-energy states have been discovered in many systems with obscure origins and significance. However, as low-energy states are naively expected to be critical to function, these observations pose important challenges. A review of known properties of low energy states covering eight photochemical systems, and options for their interpretation, are presented. A concerted experimental and theoretical research strategy is suggested and outlined, this being aimed at providing a fully comprehensive understanding. [ABSTRACT FROM AUTHOR]