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Solar driven conversion of CO2 into carbonaceous chemicals is a promising strategy to mitigate greenhouse gas emission and simultaneously store renewable energy. The rational construction of heterostructured cocatalysts represents an efficient method to improve the photocatalytic activity and selectivity for CO2 reduction. In this work, with Pd@Au core–shell nanostructures with tunable Au thickness as model cocatalysts, we demonstrate the synergism of surface strain and interfacial polarization for enhanced photoreduction of CO2 to CO. According to our experimental analysis and theoretical simulation, resulting from the mismatch in lattice parameters between the Pd core and the Au shell, compressive strain on the Au surface elevates the d-band center and improves the adsorption of the key intermediate *COOH. Meanwhile, charge polarization, driven by the difference in electronegativity between Pd and Au, accelerates the interfacial charge transfer and increases the electron density on the Au surface. It is found that both effects are dependent on the thickness of the Au shell. As a result, a three-atom-thick Au shell dramatically boosts the overall efficiency in CO2-to-CO conversion with an impressive activity of 166.3 μmol gcat−1 h−1 and selectivity of 90.6%. This study can be viewed as a means of designing photocatalysts via the simultaneous control of surface catalytic reactivity and interfacial charge transfer in cocatalysts. [ABSTRACT FROM AUTHOR]

Photocatalytic reduction of CO2 to renewable fuels offers opportunities for long-term energy storage and environmental protection. However, the lack of highly active and selective catalysts impedes the application of this reaction. Here, Janus Pd–Au heterojunctions are proposed as advanced co-catalysts for the conversion of CO2 to CH4, which achieve an unprecedented average CH4 production rate of 48.2 μmol gcat−1 h−1 with a high selectivity of 91.4%. The experimental results indicate that the interfaces between Pd and Au play multiple roles in the enhancement of CO2-to-CH4 conversion: (1) Au atoms around the interface provide the sites for the reduction of CO2 to *CO intermediates and then to CH4; (2) *H intermediates are produced on adjacent Pd atoms on the other side of the interface, which further accelerate the rate-limiting process in conversion of *CO to CH4; (3) charge re-distribution through the Pd–Au interface leads to substantial suppression of H2 and CO evolution on electron-deficient Pd and electron-rich Au, respectively. This work provides fresh insights into the rational interface design of high-performance bimetallic co-catalysts for selective CO2 photoreduction. [ABSTRACT FROM AUTHOR]

Photocatalytic conversion of CO2 into CH4 represents an appealing approach to alleviate the world's continued reliance on fossil fuels and global warming resulting from increasing CO2 concentrations in the atmosphere. However, its practical application is greatly limited by serious electron–hole recombination in the photocatalysts and the production of CO and H2 as side reactions. Herein, for the first time, it is demonstrated that the photocatalytic reduction of CO2 to CH4 can be significantly improved through the simultaneous alloying and hydriding of metal cocatalysts. The isolation of Cu and H atoms in Pd lattices play three roles in the enhancement of CO2 to CH4 conversion: 1) Cu atoms provide catalytic sites to reduce CO2 into CO and then to CH4 to suppress H2 evolution; 2) H atoms improve the electron‐trapping ability of cocatalysts; and 3) H atoms accelerate the reduction of CO to CH4, which is the rate‐limiting procedure in the conversion of CO2 into CH4. Arising from the synergistic interplay between Pd−H and Cu−CO sites, C3N4−Pd9Cu1Hx (15 mg) achieves 100 % selectivity for CH4 production with an average rate of 0.018 μmol h−1 under visible‐light irradiation. This work provides insights into the design of a cocatalyst for highly selective CO2 conversion through lattice engineering at atomic precision. Pick of the products: The photocatalytic reduction of CO2 to CH4, with a high production rate and complete selectivity is realized through the simultaneous incorporation of substitutional copper and interstitial hydrogen atoms into the lattice of palladium cocatalysts. The excellent performance can be explained by the synergistic interplay between Pd−H and Cu−CO sites in promoting the rate‐limiting reaction. [ABSTRACT FROM AUTHOR]

Photocatalytic conversion of CO2 to CH4, a promising approach to reduce the depletion of fossil fuels and concomitant global warming, is greatly limited by the production of CO and H2 by side reactions. Rational design of co-catalysts holds promise to address this grand challenge. In this paper, via the transformation from a random A1 alloy phase to an ordered B2 intermetallic phase, order engineering is performed on PdCu co-catalysts to realize enhanced photocatalytic activity and selectivity in reduction of CO2 with H2O to CH4. Based on the experimental results of PdCu co-catalysts with different ordered degrees of atomic arrangement obtained through tuning the annealing temperatures and Pd/Cu molar ratios, two effects are proposed to contribute to this enhancement: (1) the strong electronic interaction between Pd and Cu atoms in the periodic structure increases the electron trapping ability of ordered PdCu co-catalysts; (2) the periodic structure increases the number of isolated Cu atoms in the ordered PdCu co-catalysts, which act as highly active catalytic sites in the reduction of CO2 to CH4. This work represents a step toward the design of high-performance photocatalysts through lattice engineering of the co-catalysts with atomic precision. [ABSTRACT FROM AUTHOR]

Abstract: An Ag2S@MoS2 core–shell nanowire heterojunction, facilely synthesized by simultaneous sulfuration of Ag nanowires (NMs) and growth of MoS2, is used as a model system to disclose how the surface and interface structures influence the photocatalytic activity. The Ag2S@MoS2 NWs with different loading amounts of MoS2 are used as photocatalysts for H2 production. It is found that the highest photocatalytic activity is realized by a moderate loading amount of MoS2. A lower loading amount of MoS2 not only reduces the interfacial contact for insufficient electron–hole separation but also decreases the number of catalytic active sites for H2 production, while a higher loading amount of MoS2 increases the light‐shielding effect of Ag2S and extends the distance of electron transfer to the catalytic active sites for H2 production. Furthermore, with the same loading amount of MoS2, Ag2S@MoS2 NWs also exhibit superior H2 production activity in comparison with pre‐Ag2S@MoS2 NWs with MoS2 grown on pre‐synthesized Ag2S nanowires. The proposed reason is that the simultaneous sulfuration of Ag nanowires and growth of MoS2 results in an intimate contact between Ag2S and MoS2 for smooth interfacial charge transfer, while the two‐step synthetic method leads to a lower quality of the MoS2‐Ag2S interface and thus poor interelectron transfer. This work highlights the importance of a rational surface and interface design of semiconductor heterojunctions for realizing high‐performance photocatalytic applications. [ABSTRACT FROM AUTHOR]

The combination of plasmonic metal and cocatalyst with semiconductor has been widely used to simultaneously improve the efficiencies of light absorption, charge separation, and surface reaction for high‐performance photocatalysis. Despite the tremendous efforts, the ternary nanostructures suffer from two bottlenecks: 1) long distance between plasmonic metal and cocatalyst increases the chance of hot electron loss; 2) opposite transmission directions between plasmon‐induced hot electrons and semiconductor‐generated free electrons disfavor the practical application of broad‐spectrum photocatalysis. In this paper, a novel photocatalytic nanostructure, in which plasmonic Au and Pd cocatalysts are integrated into Janus heterojunction on the TiO2, is demonstrated. The advantages of the designed photocatalyst include: 1) the shortened distance between Au and Pd as well as the formation of additional channel of Au–Pd interface accelerates the hot electron transfer; 2) the opposite directions of visible‐light‐induced hot electrons and ultraviolet‐light‐excited free electrons are mediated with a unified TiO2 → Au → Pd transmission route during the broad‐spectrum photocatalysis. As a result, 15 mg of the designed photocatalyst achieves average H2 production rates of 0.79 and 7.59 µmol h−1 under visible and broad‐spectrum irradiation, respectively, much higher than those of other binary and ternary architectures consisting of TiO2, Pd, and Au. [ABSTRACT FROM AUTHOR]

Photocatalytic conversion of CO 2 into CH 4 represents an appealing approach to alleviate the world's continued reliance on fossil fuels and global warming resulting from increasing CO 2 concentrations in the atmosphere. However, its practical application is greatly limited by serious electron-hole recombination in the photocatalysts and the production of CO and H 2 as side reactions. Herein, for the first time, it is demonstrated that the photocatalytic reduction of CO 2 to CH 4 can be significantly improved through the simultaneous alloying and hydriding of metal cocatalysts. The isolation of Cu and H atoms in Pd lattices play three roles in the enhancement of CO 2 to CH 4 conversion: 1) Cu atoms provide catalytic sites to reduce CO 2 into CO and then to CH 4 to suppress H 2 evolution; 2) H atoms improve the electron-trapping ability of cocatalysts; and 3) H atoms accelerate the reduction of CO to CH 4 , which is the rate-limiting procedure in the conversion of CO 2 into CH 4 . Arising from the synergistic interplay between Pd-H and Cu-CO sites, C 3 N 4 -Pd 9 Cu 1 H x (15 mg) achieves 100 % selectivity for CH 4 production with an average rate of 0.018 μmol h -1 under visible-light irradiation. This work provides insights into the design of a cocatalyst for highly selective CO 2 conversion through lattice engineering at atomic precision., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)