Tailoring Cu-Based Electrocatalysts for Enhanced Electrochemical CO2 Reduction to Alcohols: Structure-Selectivity Relationship.

The use of CO2 as a feedstock for the production of carbon-based fuels and value-added chemicals offers a promising route toward carbon neutrality. In this study, two Cu-based electrocatalysts, namely, Cu24/N-C and Cu2/N-C, are successfully prepared by thermal treatment of Cu24 metal-organic polyhedron-loaded zeolitic imidazolate framework-8 (ZIF-8) nanocrystals (Cu24/ZIF-8) and Cu2 dinuclear compound-loaded ZIF-8 nanocrystals (Cu2/ZIF-8), respectively. Extensive structural and compositional analyses were conducted to confirm the formation of Cu nanocluster-loaded N-doped porous carbon supports in both Cu24/N-C and Cu2/N-C and Cu nanoparticles encapsulated by graphitic carbons in Cu2/N-C as well. These two Cu-based electrocatalysts exhibited different behaviors in the electrochemical CO2 reduction reaction (CO2RR). The Cu24/N-C electrocatalyst showed high selectivity for CO production, while Cu2/N-C showed a preference for alcohol generation. The excellent stability of Cu2/N-C over a 30 h continuous electrochemical reduction further highlights its potential for practical applications. The difference in electrocatalytic performance observed in the two catalysts for CO2RR was attributed to distinct catalytic sites associated with Cu nanoclusters and nanoparticles. This research reveals the significance of their structures and compositions for the development of highly selective electrocatalysts for CO2 reduction.

Cu-nanocluster-loaded N-doped porous graphitic carbon for electrochemical CO2 reduction towards syngas generation.

In this study, a novel electrocatalyst, namely Cu/N-pg-C derived from Cu-doped ZIF-8, was investigated for making syngas products with various H2/CO ratios. Different ratios of the electrocatalytic syngas products CO and H2 could be selected by adjusting the applied potential and hence tuning the transfer of electrons from N-doped graphitic carbon to the well-dispersed Cu nanoclusters.

Facile synthesis of layered double hydroxide nanosheets assembled porous structures for efficient drug delivery.

As one of the important types of two-dimensional materials, layered double hydroxides (LDHs) have been widely used in the biomedical field as carriers for drug delivery. In this case, we propose a facile synthetic method for preparing LDH-based self-assembly structures via a metal ions-mediated zeolitic imidazolate framework-8 (ZIF-8) transformation process. The as-made hierarchical porous ZIF-8@LDHs core-shell structures and porous cages of LDHs (PC-LDHs) in drug delivery systems are used to study the loading and release of small molecular weight drugs such as doxorubicin hydrochloride (DOX) and 5-fluorouracil (5-FU). The intrinsic properties and assembly structures of both carriers are investigated in depth for their impact on slow drug release. Finally, PC-LDHs outperform ZIF-8@LDHs core-shell structures in terms of drug delivery performance under various conditions, indicating that LDH nanosheets would play a decisive role in the drug delivery process. In the drug release system, scattered LDH nanosheets with smaller sizes than their assemblies are gradually produced, allowing nanodrugs to enter cancer tissues more easily across biological barriers. This study provides the preliminary preparation for an LDH-based nanomedicine platform in the field of cancer therapy.

Metalloporphyrin modified defective TiO2 porous cages with the enhanced photocatalytic activity for coupling of hydrogen generation and tetracycline removal.

Integration of molecular transition-metal complexes and semiconductors is an appealing method to develop high-performance hybrid photocatalysts based on improvement of their solar energy harvesting ability and photogenerated charge carrier separation efficiency. Herein, Cu-TCPP modified TiO2 porous cages with oxygen vacancy defects, derived from NH2-MIL-125(Ti) nanocrystals, are successfully prepared to form PC-TiO2-d/Cu-TCPP hybrids via a surface assembly process. The PC-TiO2-d/Cu-TCPP hybrid shows an enhanced photodegradation efficiency (73.7%, 95.4%) towards tetracycline in the air under visible light or the simulated sunlight irradiation compared to PC-TiO2-d (33.7%, 81.1%) within 100 min. Moreover, the photocatalytic system is applicable to coupling both processes of solar fuel production and pollutant degradation. The PC-TiO2-d/Cu-TCPP hybrid exhibits a high hydrogen evolution rate of ∼2 mmol g-1 h-1 in the aqueous solution of tetracycline in an inert atmosphere upon irradiation by the simulated sunlight. In contrast, an inferior photocatalytic performance of hydrogen evolution is observed in pure water without the addition of tetracycline. Finally, the high sustainability of PC-TiO2-d/Cu-TCPP is mainly attributed to the strong interaction between the molecular photosensitizer and the semiconductor photocatalyst by oxygen vacancies and Cu(ii) ions.

Surface Engineering of TiO2 Nanosheets to Boost Photocatalytic Methanol Dehydrogenation for Hydrogen Evolution.

Low-cost high-efficiency H2 evolution is indispensable for its large-scale applications in the future. In the research, we expect to build high active photocatalysts for sunlight-driven H2 production by surface engineering to adjust the work function of photocatalyst surfaces, adsorption/desorption ability of substrates and products, and reaction activation energy barrier. Single-atom Pt-doped TiO2-x nanosheets (NSs), mainly including two facets of (001) and (101), with loading of Pt nanoparticles (NPs) at their edges (Pt/TiO2-x-SAP) are successfully prepared by an oxygen vacancy-engaged synthetic strategy. According to the theoretical simulation, the implanted single-atom Pt can change the surface work function of TiO2, which benefits electron transfer, and electrons tend to gather at Pt NPs adsorbed at (101) facet-related edges of TiO2 NSs for H2 evolution. Pt/TiO2-x-SAP exhibits ultrahigh photocatalytic performance of hydrogen evolution from dry methanol with a quantum yield of 90.8% that is ∼1385 times higher than pure TiO2-x NSs upon 365 nm light irradiation. The high H2 generation rate (607 mmol gcata-1 h-1) of Pt/TiO2-x-SAP is the basis for its potential applications in the transportation field with irradiation of UV-visible light (100 mW cm-2). Finally, lower adsorption energy for HCHO on Ti sites originated from TiO2 (001) doping single-atom Pt is responsible for high selective dehydrogenation of methanol to HCHO, and H tends to favorably gather at Pt NPs on the TiO2 (101) surface to produce H2.