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Photocatalytically reducing CO2 by H2O into valuable carbon-containing chemicals is one of the greatest concerns for both scientific and industrial communities, due to its great potential in solving energy and environmental problems. However, the photocatalytic reduction efficiency is still much lower than the need of large-scale applications. Abilities of photocatalysts in adsorbing CO2 and splitting H2O to produce protons are crucial factors determining the photocatalytic reduction efficiency. Significant research efforts have been devoted to addressing the issues on CO2 adsorption and proton production. The present review discusses the recent progresses in improving CO2 adsorption and proton production on photocatalysts for increasing the photocatalytic reduction efficiency. Future research opportunities and challenges are also discussed. It is hoped that the present review can stimulate more deep insights on adsorption of CO2 and production of proton for increasing the photocatalytic reduction efficiency.

Hydrogenation of CO2 into methanol is promising for achieving the sustainable energy economy, but still has some problems, e.g. low methanol selectivity and high operation pressures (>10 atm). Herein, we prepared a Pt/film hybrid with highly dispersed Pt nanoparticles, and combined Pt/film with In2O3 to form a Pt/film/In2O3 catalyst. By using a dielectric barrier discharge (DBD) plasma reactor, a CO2 conversion of 37.0% and a methanol selectivity of 62.6% are achieved in the hydrogenation of CO2 with H2 on Pt/film/In2O3 at 1 atm and 30 °C. These are higher than those on Pt/In2O3 prepared by the conventional high-temperature H2 reduction (24.9% and 36.5%) and commercial Cu/ZnO/Al2O3 (25.6% and 35.1%). The high-energy electrons of the DBD plasma trigger the CO2 hydrogenation at 1 atm and 30 °C. The higher Pt nanoparticles dispersion, film and In2O3 promote the adsorption of CO2 on Pt/film/In2O3, thus enhancing the hydrogenation of CO2 into methanol. These results are helpful for efficient methanol production from CO2 hydrogenation under atmospheric pressure.

Developing noble-metal-free photocatalysts highly flexible for separating the photogenerated electron-hole pairs is crucial for the solar-energy-driven photocatalysis, but still remains an open question. Herein, we fabricated two dimensional Co3S4 nanosheets with a thickness of about 10 nm, and applied the nanosheets to support CdS nanoparticles (∼5 nm) to form a noble-metal-free CdS/Co3S4 photocatalyst with a higher ability in charge separation. In the visible-light-driven photocatalytic H2O splitting, an enhanced H2 evolution (1083.9 μmol h−1) was achieved on CdS/Co3S4, as compared with those on the CdS-nanoparticle-loaded Co3S4 nanoparticles (775.5 μmol h−1) and noble-metal-based CdS/Pt photocatalyst (566.3 μmol h−1). The enhanced photocatalytic performance is the result of the multiple roles of the Co3S4 nanosheets in the photocatalytic reaction, including promoting electron-hole separation, providing catalytically active sites and suppressing the aggregation of the CdS nanoparticles responsible for light absorption.

Temperature is one of the pivotal factors influencing mycelium growth and fruit-body formation of Flammulina velutipes. To gain insights into hyphae growth and fruit-body formation events and facilitate the identification of potential stage-specific biomarker candidates, we investigated the proteome response of F. velutipes mycelia to cold stresses using iTRAQ-coupled two-dimensional liquid chromatography tandem mass spectrometry (2D LC-MS/MS) technique. Among 1198 proteins identified with high confidence, a total of 63 displayed altered expression level after cold stress treatments. In-depth data analysis reveals that differentially expressed proteins were involved in a variety of cellular processes, particularly metabolic processes. Among the 31 up-regulated proteins, 24 (77.42%) were associated with 22 specific KEGG pathways. These up-regulated proteins could possibly serve as potential biomarkers to study the molecular mechanisms of F. velutipes mycelia response to cold stresses. These data of the proteins might provide valuable evidences to better understand the molecular mechanisms of mycelium resistance to cold stress and fruit-body formation in fungi. Biological significance Low-temperature is one of the pivotal factors in some Flammulina velutipes industrial processes influencing mycelium growth, inducing primordia and controlling fruit-body development. Preliminary study has indicated that effectively regulating cultivation could augment the yield by controlling optimal cold stress level on mycelia. However, we are still far from understanding the molecular and physiological mechanisms of adaptation of these fungi at cold stress. In the present study, the experiments reported above were undertaken to investigate chronological changes of protein expression during F. velutipes mycelia in response to cold stress by using iTRAQ-coupled 2D LC-MS/MS technique. This result would provide new insights to the underlying mycelium growth and fruit-body formation mechanisms of basidiomycetes under cold stress.

The power conversion efficiency elevation of dye-sensitized solar cell (DSSC) is limited by the incomplete dye excitation, recombination of photogenerated electrons with ions in liquid electrolyte, low electron density in conduction band (CB) of TiO2 nanoscrystalline as well as photodegradation of dye molecules. With an aim of enhancing the power conversion efficiency, here we describe an employment of SiO2 incorporated TiO2 to enhance transmission, to suppress the recombination of electron-electrolyte, to elevate the dye loading and to increase the dye photostability. We find that the highest conversion occurs at 7 wt% SiO2 in SiO2 incorporated TiO2 nanocrystallines is 9.13% (measured under standard AM1.5 test conditions) in comparison with 6.26% from pure TiO2 photoanode, giving an efficiency enhancement by 45.8%. This strategy provides new opportunities for the fabrication of highly efficient DSSCs, and the efficiency record is expected to be surpassed by scalable technique and components.