Efficient carboxylation of styrene and carbon dioxide by single-atomic copper electrocatalyst.

Electrocarboxylation of olefins with carbon dioxide (CO2) is a potential approach to produce carboxylates as synthetic intermediates of polymer and pharmaceuticals. Nonetheless, due to the intrinsic inertness of CO2 at ambient conditions, the electrocarboxylation efficiency has been quite limited, typically with high applied potentials and low current densities. In this work, we demonstrate that nitrogen-coordinated single-atomic copper sites on carbon framework (Cu/NC) served as an excellent electrocatalyst for electrocarboxylation of styrene with CO2. The Cu/NC catalyst allowed to efficiently activate CO2, followed by nucleophilic attack to carboxylate styrene to produce phenylsuccinic acid, thus leading the reaction toward the CO2 activation pathway. The enhanced CO2 activation capability enabled increased selectivity and activity for electrocarboxylation of styrene. The Faradaic efficiency of electrocarboxylation was 92%, suggesting most of the activated CO2 proceeded to react with styrene rather than direct reduction to CO or CH4. The electrocarboxylation exhibited almost 100% product selectivity toward phenylsuccinic acid, with a high partial current density of 58 mA·cm-2 at -2.2 V (vs. Ag/AgI), corresponding to an outstanding production rate of 216 mg·cm-2·h-1, substantially exceeding previously reported works. Our work suggests an exciting perspective in electrocarboxylation of olefins by rational design of CO2 activation electrocatalysts.

Oxygen vacancies enhanced cooperative electrocatalytic reduction of carbon dioxide and nitrite ions to urea.

The electrochemical reduction of carbon dioxide and nitrite ions into value-added chemicals represents one of the most promising approaches to relieve the greenhouse gases, while a critical challenge is to search for a highly effective catalyst with low energy input and high conversion selectivity. In this work, we demonstrated low-valence Cu doped, oxygen vacancy-rich anatase TiO2 (Cu-TiO2) nanotubes as a synergetic catalyst for electrochemical co-reduction of both CO2 and NO2-. The incorporation of Cu dopants in anatase TiO2 facilitated to form abundant oxygen vacancies and bi-Ti3+ defect sites, which allowed for efficient nitrite adsorption and activation. The low-valence Cu dopants also served as effective catalytic centers to reduce CO2 into CO* adsorbate. The close proximity of CO* and NH2* intermediates was beneficial for the subsequent cooperative tandem reaction to form urea via the CN coupling. This oxygen vacancy-rich Cu-TiO2 electrocatalyst enabled excellent urea production rate (20.8 µmol⋅h-1) and corresponding Faradaic efficiency (43.1%) at a low overpotential of -0.4 V versus reversible hydrogen electrode, substantially superior than those of undoped TiO2, thus suggesting an exciting approach for cooperative CO2 and nitrogen fixation.

One-dimensional Nanomaterial Electrocatalysts for CO2 Fixation.

Electroreduction of CO2 into valuable molecules or fuels is a sustainable pathway for CO2 reduction as well as energy storage. However, the premature development stage of electrocatalysts with high activity, selectivity, and durability still remains a significant bottleneck that hinders this field. One-dimensional (1D) nanomaterials, including nanorods, nanotubes, nanoribbons, nanowires, and nanofibers, are generally considered as high-activity and stable electromaterials, due to their unique uniform structures, orientated electronic and mass transport, and rigid tolerance to stress variation. During the past several years, 1D nanomaterials and nanostructures have been extensively studied due to their potentials in serving as CO2 electroreduction catalysts. In this minireview, recent studies and advances in 1D nanomaterials for CO2 eletroreduction are summarized, from the viewpoints of both computational and experimental aspects. Based on the composition, the 1D nanomaterials are studied in four categories, including metals, transition-metal oxides/nitrides, transition-metal chalcogenides, and carbon-based materials. Different parameters in tuning 1D materials are also summarized and discussed, such as the crystal facets, grain boundaries, heteroatoms doping, additives and the electrochemical tuning effects. Finally, the challenges and prospects in this direction will be discussed.

High-Performance Aqueous Zinc-Ion Battery Based on Layered H2 V3 O8 Nanowire Cathode.

Rechargeable aqueous zinc-ion batteries have offered an alternative for large-scale energy storage owing to their low cost and material abundance. However, developing suitable cathode materials with excellent performance remains great challenges, resulting from the high polarization of zinc ion. In this work, an aqueous zinc-ion battery is designed and constructed based on H2 V3 O8 nanowire cathode, Zn(CF3 SO3 )2 aqueous electrolyte, and zinc anode, which exhibits the capacity of 423.8 mA h g-1 at 0.1 A g-1 , and excellent cycling stability with a capacity retention of 94.3% over 1000 cycles. The remarkable electrochemical performance is attributed to the layered structure of H2 V3 O8 with large interlayer spacing, which enables the intercalation/de-intercalation of zinc ions with a slight change of the structure. The results demonstrate that exploration of the materials with large interlayer spacing is an effective strategy for improving electrochemical stability of electrodes for aqueous Zn ion batteries.