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Heterogenized phthalocyanine-based molecular catalysts are the ideal electrocatalytic platforms for CO2 reduction reaction (CO2RR) because of their well-defined structures and potential properties. In addition to the pursuit of catalytic performances at industrial potentials, it is equally important to explore experimental rules and design considerations behind activity and selectivity. Herein, we successfully developed a series of nickel phthalocyanines (NiPcs) with different alkyl chains immobilized on multi-walled carbon nanotubes (CNT) to unveil the structure—performance relationship for electrocatalytic CO2RR in neutral electrolyte. Interestingly, a volcano-type trend was found between the activity for CO2-to-CO conversion and alkyl chain lengths of NiPcs on CNT. Experimental results further indicate that their electrocatalytic CO2RR activities are highly related to the molecular dispersion and the heterointerfacial charge transfer capability adjusted by the alkyl chains. Particularly, the optimized electrocatalyst via accurate clipping at the molecular level exhibits an ultrahigh activity with Faradaic efficiency of CO up to 99.52%. [ABSTRACT FROM AUTHOR]

Designed alloy catalysts have shown promise in structure-controlled growth of single-wall carbon nanotubes (SWCNTs). However, due to the high-dimensional growth parameter space and low efficiency of the conventional trial-and-error optimizing approach, it is still challenging to explore and to establish the relations between catalyst compositions and the structure of SWCNTs. Here, we present a high-throughput strategy to investigate the statistical patterns in catalyst activity and selective growth of SWCNTs using Co/Pt/Mo ternary catalysts. Statistical analysis reveals that in the Co/Pt/Mo ternary diagram, there is an active region in the Co-rich Co–Mo corner to grow SWCNTs with high yield (≥25 tubes/μm2) and high quality (I G / I D ≥ 40). Enriched semiconducting (s-) SWCNTs with a purity higher than 90% were obtained along the boundary of the high yield region, near the Co–Pt axis. The statistical patterns of the yield, quality and selectivity are associated with the alloy composition, revealing a negative correlation between the yield and enrichment of s-SWCNTs. High-resolution transmission electron microscope characterization shows that a Co–Pt alloy catalyst with a uniform size distribution facilitates the s-SWCNT enrichment. And the separate phases of a Co–Mo/Co catalyst stabilize the active Co phase, leading to long catalyst lifetime and high yield of SWCNTs. A high-throughput strategy is developed to investigate the statistical patterns of the catalyst activity and the selective growth of single-wall carbon nanotubes (SWCNTs) grown from Co/Pt/Mo ternary catalysts. The structure of Co/Pt and Co/Mo catalysts linked with SWCNTs are further identified by using high-resolution transmission electron microscope. [Display omitted] [ABSTRACT FROM AUTHOR]

High-purity (∼96%) isolated s-SWCNT film with narrow diameter distribution were prepared on large scale by oxygen-assisted FCCVD method. [Display omitted] • Bulk isolated s-SWCNT films with a high content of 96% were selectively prepared. • O 2 was found to play function on catalyst particle size and s-SWCNT diameter. • FET devices show good performance verifying the enrichment of s-SWCNTs. Semiconducting single-wall carbon nanotubes (s-SWCNTs) are promising for use in flexible electronics as a channel material. However, it remains a big challenge to directly grow high purity, high-quality s-SWCNTs in large scale. Here we report the synthesis of isolated s-SWCNTs by an oxygen-assisted floating catalyst chemical vapor deposition method. By controlling the density of nucleated SWCNTs, isolated or small-bundled, rather than large-bundled SWCNTs were generated in a floating state, so that the oxygen introduced could more efficiently selectively etch the metallic-SWCNTs formed. In addition, it was found that the oxygen also functions in limiting the size of Fe catalyst nanoparticles in a narrow range of 5–8 nm. As a result, isolated s-SWCNTs with a narrow diameter distribution were synthesized. The content of s-SWCNTs reached ∼96%, and the percentage of isolated tubes was estimated to be ∼83%. Thin-film transistors (TFTs) constructed using the s-SWCNT film showed high on/off ratios ranging from 2.1 × 104 to 1.2 × 106, verifying the effective enrichment of s-SWCNTs. [ABSTRACT FROM AUTHOR]