Guided Assembly of Microporous/Mesoporous Manganese Phosphates by Bifunctional Organophosphonic Acid Etching and Templating

Abstract

Manganese (Mn)‐based compounds are important materials for both energy conversion and energy storage. Unfortunately, it has been a significant challenge to develop highly ordered microporous/mesoporous structures for them to provide more active sites for these applications. In order to do so using the soft‐templating method, three conditions have to be met, namely, a strong interaction between the inorganic precursor and the organic templates; eliminating the formation of bulk manganese phosphate; and the preservation of the manganese phosphate framework without it collapsing upon template removal. Herein, a soft‐templating approach is reported using an organophosphonic acid (n‐hexylphosphonic acid) as both the etching and the templating agent, followed by high‐vacuum‐assisted annealing. This approach simultaneously satisfies the above conditions. Both microporous and mesoporous manganese phosphates with uniform pore sizes and well‐defined pore structures are obtained. The utilization of the organophosphonic acid is shown to be the key in the transformation from bulk manganese oxide into a highly ordered microporous phosphate. A very high surface area of 304.1 m2 g−1 is obtained for the microporous manganese phosphate, which is the highest among the reported values for Mn‐based compounds. The ultrafine micropores and high specific surface area of our manganese phosphate promote electrocatalytic activity for the oxygen evolution reaction.

Strong Metal Phosphide–Phosphate Support Interaction for Enhanced Non‐Noble Metal Catalysis

“…[ 18,27–29 ] In order to keep the catalysts active, introducing new catalytic active sites is one of the most attractive strategies. [ 22,30–37 ] The incorporation of phosphorus (P) into metal nanoparticles (metal phosphide) can stabilize the metal state and modify the electronic state of metal species, which is beneficial to the catalytic performance and selectivity of hydrogenation. [ 34,35,37 ] In addition to the active sites, the support also plays an important role in catalytic process.…”

“…[ 26 ] As a widely used and excellent catalyst in various electrocatalytic reaction, manganese phosphate displays high electrical conductivity and catalytic activity due to the stabilization of the active sites by the phosphate framework and better electron transfer during catalytic reactions. [ 36 ] Combining the advantages of metal phosphides and phosphates to construct SMSI may have great potential to achieve highly active and stable catalyst for efficient hydrogenation.…”

Single-Atom Mn–N4 Catalyst with Electron-Rich O and S Self-Doping for Cooperative Nonradical and Radical Oxidation: Overlooked Nonmetal Heteroatomic Sites

“…NOSPC and Mn SA –N–C O,S exhibited a similar ultrathin nanosheet with a smooth surface (Figures b and S3), and no obvious aggregation of Mn nanoparticles could be observed in the high-resolution TEM (HR-TEM) image of Mn SA –N–C O,S (Figure c). Moreover, Mn SA –N–C O,S exhibited predominantly microporous structures (Figure S4), and a remarkable specific surface area (310.19 m 2 /g) and pore volume (0.14 cm 3 /g), providing abundant active sites and facilitating mass transfer to ultimately enhance its catalytic activity . The energy dispersion spectroscopy (EDS) images under the TEM model (Figure d) revealed that C, N, O, S, and Mn atoms are uniformly distributed in Mn SA –N–C O,S .…”

Biocatalytic and Antioxidant Nanostructures for ROS Scavenging and Biotherapeutics

“…The transition metal (Mn, Fe, and Vn) compounds are highly redox‐active, and the pharmacokinetic researches proved that natural Mn‐SOD is much better than Cu/Zn‐SOD and Fe‐SOD. [ 64,65 ] MnO 2 NPs are the most extensively investigated biocatalytic nanostructures, which can catalyze the H 2 O 2 into O 2 and H 2 O. Owing to the co‐existence of Mn 2+ and Mn 3+ , Mn 3 O 4 NPs are capable of eliminating O 2 •− by the dismutation of O 2 •− into O 2 and H 2 O 2 and catalyze the elimination of H 2 O 2 . The modeled Fenton‐like reaction between iron‐based NPs and H 2 O 2 may generate ROS.…”