The purpose of this study is to develop novel P-Mo-V heteropoly compound catalysts for the oxidation of methacrolein to methacrylic acid. The introduction of Cu, as a modifying element, was employed to enhance the catalytic performance. Experimental results show that the addition of Cu significantly improved the catalyst performance, increasing the conversion rate of methacrolein from 17.2% to 84.2%, while the yield of methacrylic acid was boosted from 5.5% to 51.7%. A series of characterization results showed that both P-Mo-V and Cu-P-Mo-V catalysts primarily exhibited the crystal phase of [PMo₁₂O₄₀]³⁻, with a small amount of [PMo₁₁VO₄₀]³⁻ phase. However, the Cu-P-Mo-V catalyst exhibited much better oxidation–reduction ability compared to the P-Mo-V catalyst. Isolated Cu atoms were found to exist in a highly decentralized tetrahedral coordination structure, bridged by oxygen atoms within the heteropoly compound framework. The addition of Cu resulted in notable alterations in the modulation of the surface electronic structure, enhancement of oxidation–reduction ability, and optimization of the reaction pathway, thereby improving the overall catalytic activity of the catalyst. This study not only provides new insights into the modification of P-Mo-V heteropoly compound catalysts but also lays a foundation for understanding their catalytic mechanisms in organic synthesis reactions, demonstrating the potential of modifying elements in improving catalyst performance.

Chiral inorganic materials have attracted great attention owning to their unique physical and chemical properties attributed to the symmetry-breaking of their nanostructures. Chiral inorganic materials can be endowed with chiral geometric configurations from achiral space group crystals through lattice twisting, screw dislocations or hierarchical self-assembled spiral morphologies, showing various characteristic chiral anisotropy. However, the multilevel chirality in chiral nickel molybdate films (CNMFs) remains to be elaborately excavated. In this paper, we report three hierarchical levels of chirality in CNMFs, spanning from the atomic to the micron scale, including primary helically coiled nanoflakes with twisted atomic crystal lattices, secondary helical stacking of layered nanoflakes, and tertiary asymmetric morphology between adjacent nanoparticles. Our findings may enrich the chiral self-assembly structural types and provide valuable insights for the comprehensive analysis path of hierarchical chiral crystals.