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A series of Fe-based catalysts with accurately controlled amounts of Na are synthesized to investigate the relationship between the promoter and the catalytic performance for CO 2 hydrogenation to alkenes. With the increasing amount of Na, both CO 2 conversion and alkenes selectivity increase at low and moderate amounts and then plateau (with the highest to be 36.8% and 64.3%, respectively), while the corresponding methane production decreases to 7.2%. It is found that the addition of Na enhances the adsorption of CO 2 , facilitates the formation and stability of active species Fe 5 C 2 , and inhibits the secondary hydrogenation of alkenes. All these effects lead to the desirable catalytic performance. Besides, it is observed that the content of Fe 5 C 2 is related to the amount of Na. This study can provide scientific guidance to the design and the synthesis of high-efficiency catalysts for CO 2 hydrogenation to high-value chemicals.

Ultrathin nanosheets have great potential for photocatalytic applications,however,suffer from enlarged band gap and narrowed visible-light-responsive range due to the quantum confinement effect. Herein, we report an ovel redox strategy for efficient preparation of ultrathin crystalline amidefunctionalizedc ovalent-triazine-framework nanosheets (CTF NSs) with enhanced visible light absorption. The CTF NSs exhibited photocatalytic hydrogen (512.3 mmol h À1 )a nd oxygen (12.37 mmol h À1 )e volution rates much higher than that of pristine bulk CTF.Photocatalytic overall water splitting could be achieved with efficient stoichiometric H 2 (5.13 mmol h À1 ) and O 2 (2.53 mmol h À1 )e volution rates under visible light irradiation. Experimental and theoretical analysis revealed that introduction of amide groups as electron donor optimized the band structure and improve its visible-light absorption, hydrophilicity and carrier separation efficiency,thus resulting in the enhanced photocatalytic performance.The well-dispersed CTF NSs could be easily cast onto asupport as athin film device and demonstrate excellent photocatalytic activity (25.7 mmol h À1 m À2 for hydrogen evolution).

The effect of conditioner aggressiveness is investigated in interlayer dielectric polishing on three types of pad. A method using confocal microscopy is used to analyze the effect of conditioner aggressiveness on pad–wafer contact. Results show that a more aggressive conditioner produces a higher interlayer dielectric polishing rate while at the same time a pad surface with fewer contacting summits and less contact area. It is found that the ratio of the contacting summit density to the contact area fraction is more important than either parameter measured separately since the ratio determines the mean real contact pressure. Modeling results based on contact area measurements agree well with experimental results. Moreover, it is found that a more aggressive disc also generates a thicker slurry film at the pad–wafer interface. This is in agreement with our general findings regarding pad asperity height distribution obtained using confocal microscopy.

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