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As one of the most critical approaches to resolve the energy crisis and environmental concerns, carbon dioxide (CO 2 ) photoreduction into value-added chemicals and solar fuels (for example, CO, HCOOH, CH 3 OH, CH 4 ) has attracted more and more attention. In nature, photosynthetic organisms effectively convert CO 2 and H 2 O to carbohydrates and oxygen (O 2 ) using sunlight, which has inspired the development of low-cost, stable, and effective artificial photocatalysts for CO 2 photoreduction. Due to their low cost, facile synthesis, excellent light harvesting, multiple exciton generation, feasible charge-carrier regulation, and abundant surface sites, semiconductor quantum dots (QDs) have recently been identified as one of the most promising materials for establishing highly efficient artificial photosystems. Recent advances in CO 2 photoreduction using semiconductor QDs are highlighted. First, the unique photophysical and structural properties of semiconductor QDs, which enable their versatile applications in solar energy conversion, are analyzed. Recent applications of QDs in photocatalytic CO 2 reduction are then introduced in three categories: binary II-VI semiconductor QDs (e.g., CdSe, CdS, and ZnSe), ternary I-III-VI semiconductor QDs (e.g., CuInS 2 and CuAlS 2 ), and perovskite-type QDs (e.g., CsPbBr 3 , CH 3 NH 3 PbBr 3 , and Cs 2 AgBiBr 6 ). Finally, the challenges and prospects in solar CO 2 reduction with QDs in the future are discussed., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Eosin Y, a well-known economical alternative to metal catalysts in visible-light-driven single-electron transfer-based organic transformations, can behave as an effective direct hydrogen-atom transfer catalyst for C-H activation. Using the alkylation of C-H bonds with electron-deficient alkenes as a model study revealed an extremely broad substrate scope, enabling easy access to a variety of important synthons. This eosin Y-based photocatalytic hydrogen-atom transfer strategy is promising for diverse functionalization of a wide range of native C-H bonds in a green and sustainable manner., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The increasing demand for sustainable and environmentally benign energy has stimulated intense research to establish highly efficient photo-electrochemical (PEC) cells for direct solar-to-fuel conversion via water splitting. Light absorption, as the initial step of the catalytic process, is regarded as the foundation of establishing highly efficient PEC systems. To make full use of visible light, sensitization on photoelectrodes using either molecular dyes or semiconducting quantum dots provides a promising method. In this field, however, there remain many fundamental issues to be solved, which need in-depth study. Here, fundamental knowledge of PEC systems is introduced to enable readers a better understanding of this field. Then, the development history and current state in both molecular dye- and quantum dot-sensitized photocathodes for PEC water splitting are discussed. A systematical comparison between the two systems has been made. Special emphasis is placed on the research of quantum dot-sensitized photocathodes, which have shown superiority in both efficiency and durability towards PEC water splitting at the present stage. Finally, the opportunities and challenges in the future for sensitized PEC water-splitting systems are proposed.

To achieve sustainable production of hydrogen (H 2 ) through water splitting, establishing efficient and earth-abundant electrocatalysts is of great necessity. Morphology engineering of graphene is now shown to modulate the electronic structure of carbon skeleton and in turn endow it with excellent ability of proton reduction. Three-dimensional (3D) graphene networks with a high density of sharp edge sites are synthesized. Electrocatalytic measurements indicate that the obtained 3D graphene networks can electrocatalyze H 2 evolution with an extremely low onset potential of about 18 mV in 0.5 m H 2 SO 4 solution, together with good stability. A combination of control experiments and density functional theory (DFT) investigations indicates that the exceptional H 2 evolution performance is attributed to the abundant sharp edge sites of the advanced frameworks, which are responsible for promoting the adsorption and reduction of protons., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Solar H 2 evolution of CdSe QDs can be significantly enhanced simply by introducing a suitable hole-accepting-ligand for achieving efficient hole extraction and transfer at the nanoscale interfaces, which opens an effective pathway for dissociation of excitons to generate long-lived charge separation, thus improving the solar-to-fuel conversion efficiency.