Atomically dispersed Pd catalysts in graphyne nanopore: formation and reactivity

Single and double transition metal atoms doped graphdiyne for highly efficient electrocatalytic reduction of nitric oxide to ammonia

The electrocatalytic conversion of nitric oxide (NORR) to ammonia (NH3) represents a pivotal approach for sustainable energy transformation and efficient waste utilization. Designing highly effective catalysts to facilitate the conversion of NO into NH3 remains a formidable challenge. In this work, the density functional theory (DFT) is used to design NORR catalysts based on single and double transition metal (TM:Fe, Co, Ni and Cu) atoms supported by graphdiyne (TM@GDY). Among eight catalysts, the Cu2@GDY is selected as a the most stable NORR catalyst with high NH3 activity and selectivity. A pivotal discovery underscores that the NORR mechanism is thermodynamically constrained on single atom catalysts (SACs), while being governed by electrochemical processes on double atom catalysts (DACs), a distinction arising from the different d-band centers of these catalysts. Therefore, this work not only introduces an efficient NORR catalyst but also provides crucial insights into the fundamental parameters influencing NORR performance.

Pd Clusters on Schiff Base–Imidazole-Functionalized MOFs for Highly Efficient Catalytic Suzuki Coupling Reactions

Subnanometer noble metal clusters have attracted much attention because of abundant low-coordinated metal atoms that perform excellent catalytic activity in various catalytic processes. However, the surface free energy of metals increases significantly with decreasing size of the metal clusters, which accelerates the aggregation of small clusters. In this work, new Schiff base–imidazole-functionalized MOFs were successfully synthesized via the postsynthetic modification method. Highly dispersed Pd clusters with an average size of 1.5 nm were constructed on this functional MOFs and behaved excellent catalytic activity in the Suzuki coupling of phenyboronic acid and bromobenzene (yield of biaryl >99%) under mild reaction conditions. Moreover, the catalyst can be reused six times without loss of activity. Such catalytic behavior is found to closely related to the surface functional groups that promote the formation of small Pd⁰ clusters in the metallic state.

High-performance single-atom Ni catalyst loaded graphyne for H2O2 green synthesis in aqueous media

The electrochemical synthesis of hydrogen peroxide (H₂O₂) provides a greener and more efficient method compared with classic catalysts containing toxic metals. Herein, we used first-principles density functional theory (DFT) calculations to investigate 174 different single-atom catalysts with graphyne substrates, and conducted a three-step screening strategy to identify the optimal noble metal-free single atom catalyst. It is found that a single Ni atom loaded on γ-graphyne with carbon vacancies (Ni@V-γ-GY) displayed remarkable thermodynamic stability, excellent selectivity, and high activity with an ultralow overpotential of 0.03 V. Furthermore, based on ab-initio molecular dynamic and DFT calculations under the H₂O solvent, it was revealed that the catalytic performance for H₂O₂ synthesis in aqueous phase was much better than that in gas phase condition, shedding light on the hydrogen bond network being beneficial to accelerate the transfer of protons for H₂O₂ synthesis.

Single and double boron atoms doped nanoporous C2N-h2D electrocatalysts for highly efficient N2 reduction reaction: a density functional theory study

The electrocatalytical process is the most efficient way to produce ammonia (NH₃) under ambient conditions, but developing a highly efficient and low-cost metal-free electrocatalysts remains a major scientific challenge. Hence, single atom and double boron (B) atoms doped 2D graphene-like carbon nitride (C₂N-h2D) electrocatalysts have been designed (B@C₂N and B₂@C₂N), and the efficiency of N₂ reduction reaction (NRR) is examined by density functional theory calculation. The results show that the single and double B atoms can both be strongly embedded in natural nanoporous C₂N with superior catalytic activity for N₂ activation. The reaction mechanisms of NRR on the B@C₂N and B₂@C₂N are both following an enzymatic pathway, and B₂@C₂N is a more efficient electrocatalyst with extremely low overpotential of 0.19 eV comparing to B@C₂N (0.29 eV). In the low energy region, the hydrogenation of N₂ is thermodynamically more favorable than the hydrogen production, thereby improving the selectivity for NRR. Based on these results, a new double-atom strategy may help guiding the experimental synthesis of highly efficient NRR electrocatalysts.

Molecule-level graphdiyne coordinated transition metals as a new class of bifunctional electrocatalysts for oxygen reduction and oxygen evolution reactions

Graphdiyne (GDY) could provide a unique platform for synthesizing uniform single-atom catalysts (SACs) with high catalytic activity toward oxygen reduction (ORR) and oxygen evolution (OER) reactions.