Structures and Single-Molecule Magnet Behavior of Dy3 and Dy4 Clusters Constructed by Different Dysprosium(III) Salts.

Using the Schiff base ligand H2L-pyra (N'-(2-hydroxybenzoyl)pyrazine-2-carbohydrazonamide) with multiple dentate sites, the trinuclear DyIII-based complex [Dy3(HL-pyra)2(L-pyra)2(CH3COO)3]·2H2O (1) was synthesized. By analyzing the fragmented assembly process and fine-tuning the bridging anions, complex [Dy4(HL-pyra)2(L-pyra)4(NO3)2(H2O)2]·8H2O (2) with different nuclear numbers was successfully synthesized. Magnetic studies demonstrated that 1 did not exhibit magnetic relaxation behavior under the external field; however, 2 exhibited zero-field single-molecule magnetic relaxation behavior with an effective energy barrier (Ueff) of 197.44 K. This is attributed to the improved anisotropy of the single ion after the normalization of the crystal structure, thus realizing the molecular magnetic switching. Moreover, magnetic dilution analysis of 2 demonstrated that the weak magnetic interaction between metal ions inhibited the occurrence of quantum tunneling of magnetization (QTM), resulting in high-performance single-molecule magnet (SMM) behavior. The reasons for the magnetic difference between these two complexes were analyzed using ab initio calculation and magneto-structural correlations. This study provides a reasonable prediction of the ideal configuration of the approximately parallelogram DyIII-based SMMs, thus offering an effective approach for synthesizing Dy4 complexes with excellent properties.

Co0.9Co0.1S Nanorods with an Internal Electric Field and Photothermal Effect Synergistically for Boosting Photocatalytic H2 Evolution.

The paper reports a strategy to synthesize Cd0.9Co0.1S nanorods (NRs) via a one-pot solvothermal method. Remarkably, the pencil-shaped Cd0.9Co0.1S NRs with a large aspect ratio and good polycrystalline plane structure significantly shorten the photogenerated carrier transfer path and achieve fast separation. An appropriate amount of Co addition enhances visible light-harvesting and generates a photothermal effect to improve the surface reaction kinetics and increases the charge transfer rate. Moreover, the internal electric field facilitates the separation and transfer of carriers and effectively impedes their recombination. As a result, the optimized Cd0.9Co0.1S NRs yield a remarkable H2 evolution rate of 8.009 mmol·g-1·h-1, which is approximately 7.2 times higher than that of pristine CdS. This work improves the photocatalytic hydrogen production rate by tuning and optimizing electronic structures through element addition and using the photothermal synergistic effect.

NO reduction with CO over a highly dispersed Mn/TiO2catalyst at low temperature: a combined experimental and theoretical study.

A highly dispersed Mn/TiO2catalyst, which has high efficiency for NO conversion with CO and almost completed N2selectivity at a low-temperature range (350-550 K), was investigated using experimental and DFT theoretical calculation. The characterization results illustrated that the catalyst assembled with nanoparticles and the Mn doping into the TiO2surface lattice led to the formation of Mn-O-Ti configuration, which enhanced the dispersion of Mn on the body of TiO2. The DFT study mapped out the complete catalytic cycle, including reactants adsorption, oxygen vacancy generation, N2O intermediates formation, N2formation in Eley-Rideal (ER), Langmuir-Hinshelwood, and termolecular Eley-Rideal mechanisms. With thermodynamic and kinetic analysis combined with experimental results, the ER reaction process was considered to be the fundamental mechanism over the highly dispersed Mn/TiO2catalyst. The calculation results indicated that N2O was a significant intermediate. However, the rapid N2O reduction process led to high N2selectivity. The rate-limiting step was the deoxygenation step of NO-MnOv/TiO2from N-O bond scission. The active site Mn-Ovpair embedded in Mn/TiO2was responsible not only for the formation of N-Mn/TiO2in the ER-1 step but also for the N2O deoxygenation process to make the final product N2in the ER-2 step. The synergetic effect between Mn 3d electron and the oxygen vacancy of TiO2were responsible for the catalytic activity of Mn/TiO2.