CO₂-assisted oxidative dehydrogenation of ethane (CO₂-ODHE) and dry reforming of ethane (DRE) have provided a promising way to simultaneously upgrade CO₂ and ethane to produce value-added industrial feedstocks, such as syngas (CO and H₂), or ethylene. CeO₂-supported Pd bimetallic catalysts have been demonstrated to be efficient catalysts for these reactions. In particular, the Pd-O-Ce interface and Pd-O-Fe (or Pd-O-In) interface were verified as the key active sites for producing syngas and ethylene, respectively. However, how to regulate the amount of interface to further enhance the product yield is still a major challenge in this area. In this study, we show that the ratio of the Pd-O-Ce interface can be optimized through the CeO₂ nano-island strategy. CeO₂ nano-islands with different loadings and sizes are grafted onto the high-surface-area SiO₂, and are then used for anchoring PdFe_n bi-metals, thus leading to the formation of interfaces with different amounts of Pd-O-Ce. The results show that when the Ce loading reaches 15 wt%, the supported PdFe_n catalyst has the highest ratio at the Pd-O-Ce interface, resulting in a significant increase in the syngas yield (879.1μmol · g^-1 · min^-1 for CO and 508.1μmol · g^-1 · min^-1 for H₂ respectively), which is the best among all the reported state-of-the-art catalysts in the literature. At the same time, the ethylene production rate can be maintained at a high level of 172.5 μmol · g^-1 · min^-1.

Supported metal catalysts are widely used in the modern chemical industry. The electronic interaction between supports and active components is of great significance for heterogeneous catalysis. Graphdiyne (GDY), a new type of carbon allotrope with sp-hybridized carbon atoms, π conjugate structure, and electron transmission capability, is a promising candidate as catalyst support. Recent years have witnessed the rapid progress of GDY-supported metal catalysts for different catalysis reactions. Considering that most processes in the current chemical industry are thermocatalytic reactions, we herein give an overview about the advances and particular characteristics of GDY-supported catalysts in these reactions. The geometric structure and electronic properties of GDY are first introduced. Then, the synthesis methods for GDY-supported metal catalysts and their applications in thermocatalytic reactions are discussed, in which the effect of electronic interaction on catalytic performance is highlighted. Finally, the current challenges and future directions of GDY-supported metal catalysts for thermocatalysis are proposed. It is expected that this review will enrich our understanding of the advances of GDY as a superior support for metal catalysts in thermocatalytic reactions.

MXenes are promising supports for anchoring metal single atoms due to their versatile composition, well-defined nanostructures, and suitable conductivity. However, metal single atoms are usually coordinated with surface terminal groups (-O, -OH, -Cl, etc.) of MXenes via conventional wet-impregnation, resulting in limited electronic structure modification. Through a NiCl₂ molten salt etching method, we observed that Ni single atoms could be in-situ doped in the lattice of MXenes analogue TiC_0.5N_0.5 support (denoted as Ni₁/TiC_0.5N_0.5), resulting in much larger charge transfer from Ni atoms to adjacent Ti atoms, and thus increasing the electronic density of these Ti atoms. When used for NO₂ sensing, Ni₁/TiC_0.5N_0.5 exhibited excellent response sensitivity (ultra-low limit of detection ~ 10 ppb), selectivity, and good stability at room temperature. This study provides an effective strategy for producing MXenes analogue supported metal single atoms for potential application in gas sensing.

Single-atom catalysts (SACs) with the advantages of homogeneous and heterogeneous catalysts have become a hot-spot in catalysis field. However, for lack of metal–metal bond in SACs, H₂ has to go through heterolytic dissociation pathway, which has higher barrier than homolytic dissociation pathway, and thus limits the hydrogenation activity of SACs. Herein, we propose and demonstrate through constructing synergistic iridium single atoms and nanoparticles co-existed catalyst (denoted as Ir_1+NPs/CMK) to boost the catalytic activity of quinoline hydrogenation. Both experimental and density functional theory calculation results confirm that Ir₁ single sites activate quinoline, while Ir nanoparticles boost hydrogen dissociation. H atoms generated at Ir nanoparticles migrate to the quinoline bounded Ir₁ single sites to complete hydrogenation. The Ir_1+NPs/CMK catalyst exhibits much higher reactivity with turnover frequency of 7,800 h⁻¹ than those counterpart Ir₁/CMK and Ir_NPs/CMK catalysts, and is 20,000 times higher activity of commercial Ir/C benchmark catalyst for hydrogenation of quinoline under the same reaction conditions. This synergistic catalysis strategy between single atoms and nanoparticles provides a solution to further improve the performance of SACs for hydrogenation.

Single atom catalysts (SACs) with metal₁-N_x sites have shown promising activity and selectivity in direct catalytic oxidation of benzene to phenol. The reaction pathway is considered to be involving two steps, including a H₂O₂ molecule dissociated on the metal single site to form the (metal₁-N_x)=O active site, and followed by the dissociation of another H₂O₂ on the other side of metal atom to form O=(metal₁-N_x)=O intermediate center, which is active for the adsorption of benzene molecule via the formation of a C-O bond to form phenol. In this manuscript, we report a Cu SAC with nitrogen and oxygen dual-coordination (Cu₁-N₃O₁ moiety) that doesn’t need the first H₂O₂ activation process, as verified by both experimental and density function theory (DFT) calculations results. Compared with the counterpart nitrogen-coordinated Cu SAC (denoted as Cu₁/NC), Cu SAC with nitrogen and oxygen dual-coordination (denoted as Cu₁/NOC) exhibits 2.5 times higher turnover frequency (TOF) and 1.6 times higher utilization efficiency of H₂O₂. Particularly, the coordination number (CN) of Cu atom in Cu₁/NOC maintains four even after H₂O₂ treatment and reaction. Combining DFT calculations, the dynamic evolution of single atomic Cu with nitrogen and oxygen dual-coordination in hydroxylation of benzene is proposed. These findings provide an efficient route to improve the catalytic performance through regulating the coordination environments of SACs and demonstrate a new reaction mechanism in hydroxylation of benzene to phenol reaction.

Iron oxide is a promising anode material for lithium ion batteries, but it usually exhibits poor electrochemical property because of its poor conductivity and large volume variation during the lithium uptake and release processes. In this work, a double protection strategy for improving electrochemical performance of Fe₃O₄ nanoparticles through the use of decoration with multi-walled carbon nanotubes and reduced graphene oxides networks has been developed. The resulting MWCNTs-Fe₃O₄-rGO nanocomposites exhibited excellent cycling performance and rate capability in comparison with MWCNTs-Fe₃O₄, MWCNTs-Fe₃O₄ physically mixed with rGO, and Fe₃O₄-rGO. A reversible capacity of ~680 mA·h·g^-1 can be maintained after 100 cycles under a current density of 200 mA·g^-1.