Confining active nanoparticles within specific nanoscale spaces is a promising strategy to improve the catalytic activity, selectivity and stability of catalysts. In this study, we present a lattice-matching approach to confine Co particles within ZnO layers (ZnO/Co/ZnO) for CO₂ hydrogenation, a critical and challenging reaction in the field of CO₂ utilization and energy production. XRD patterns reveal that the lattice mismatch between ZnO and hexagonal wurtzite CoO (w-CoO) is only 0.18%, facilitating the epitaxial growth of w-CoO on the ZnO surface, or vice versa. This minimal mismatch enables the successful confinement of w-CoO within the ZnO interlayers. This advanced methodology can also be adapted to diverse ZnO morphologies, allowing the optimization of the confined catalyst microstructure. Significantly, when Co particles are confined within the interlayer of ZnO, they exhibit excellent catalytic activity, achieving a rate of 15.8 μ ${\text{mol}}_{{\text{CO}}_{\text{2}}}\cdot {\text{g}}_{\text{Co}}^{-\text{1}}\cdot {\text{s}}^{-\text{1}}$ for CO₂ hydrogenation reaction. Moreover, no appreciable deactivation was observed even after 700 h of continuous operation. These results introduce a novel approach for the development of confined catalysts with enhanced activity and long-term stability.

Graphitic carbon nitride (C₃N₄) is a promising photocatalyst due to its suitable band gap and polymer properties, but its efficiency is limited by the poor separation of photoinduced electron/hole (e^–/h⁺) pairs. To address this issue, we propose creating N vacancies within the layers and bridging K single-atoms between the C₃N₄ layers through the self-assembly of potassium citrate and melamine–urea monomers. The introduction of N vacancies disrupts the symmetry of C₃N₄, promoting electron transfer along the delocalized π-conjugated network, while the presence of K atoms provides channels for electron transfer between the layers by forming N–K–N bridges, thereby leading to significant enhancement in the separation and transfer of e^–/h⁺ pairs across spatial dimension. As expected, the co-modified C₃N₄, with N vacancies and K single-atoms (designated as CN-K-V_N), exhibits excellent photocatalytic performance, with reaction rate constant of 9.69 × 10⁻² min⁻¹ (7.39 × 10⁻² min⁻¹ in real water environment) for tetracycline, achieving 80% degradation of tetracycline within 20 min. The reaction mechanism, as well as the toxicity of the degradation intermediates, is deeply discussed. This study provides a strategy to enhance the spatial separation of electrons for photocatalyst, highlighting its significance role in photocatalysis.

Catalytic transfer hydrogenation (CTH) is a green and efficient pathway for selective hydrogenation of unsaturated aldehydes and ketones. However, managing the abilities of solid catalysts to adsorb substrates and to convert them into desired products is a challenging task. Herein, we report the synthesis of carbon coated LaFe_0.92Pd_0.08O₃ composites (LFPO-8@C) for CTH of benzaldehyde (BzH) into benzyl alcohol (BzOH), using isopropanol (IPA) as hydrogen source. The coating with carbon improves the ability to adsorb/transfer reactants from solution to active sites, and the doping of Pd²⁺ at Fe³⁺ site strengthens the ability of LaFeO₃ to convert BzH into BzOH. A balanced point between them (i.e., abilities to adsorb BzH and to convert BzH into BzOH) is obtained at LFPO-8@C, which exhibits a BzOH formation rate of 3.88 mmol·g_cat⁻¹·h⁻¹ at 180 °C for 3 h, which is 1.50 and 2.72 times faster than those of LFPO-8 and LaFeO₃@C. A reaction mechanism is proposed, in which the acidic sites (e.g., Fe⁴⁺, oxygen vacancy) are used for the activation of C=O bond of BzH and O–H bond of IPA, and the basic sites (e.g., lattice oxygen) for the activation of α–H (O–H) bond of IPA.

Several exfoliation methods including thermal treatment in air and hydrogen, ultrasonication, and chemical treatment with sodium borohydride were applied to modify the properties of bulk graphitic carbon nitride (g-CN). The prepared samples were characterized by X-ray diffraction, X-ray photoemission spectroscopy, Fourier transform infrared spectroscopy, UV-Vis diffuse reflectance spectroscope and N₂ physisorption, and their photocatalytic performances were evaluated via the degradation of organic pollutants in aqueous solution. The results indicated that the exfoliation methods affect greatly on the physicochemical and photocatalytic properties of g-CN, and the optimum sample can be obtained by thermal treating in air (g-CN_A), showing 99.87% conversion at 40 min for the photocatalytic degradation of tetracycline hydrochloride, and the performance was preserved even after four cycles. The mechanism on the reaction intermediates with trapping experiments indicated that superoxide anion radicals (·O₂^–) are the main active species of the reaction.