Abstract Developing efficient and durable electrocatalysts for alkaline seawater hydrogen evolution remains challenging because of sluggish water dissociation kinetics. Herein, we report a defect-rich d-p orbital-hybridized Os/o-CNTs electrocatalyst (dph-Osdef/o-CNTs) prepared by rapid room-temperature NaBH4 reduction. The partially oxidized CNT support anchors defective Os nanoclusters and induces C–Os/C–O–Os electronic coupling, generating electron-deficient Os sites with modulated 5d electronic structures. In alkaline simulated seawater (1 M NaOH + 3.5 wt % NaCl), dph-Osdef/o-CNTs requires only 91 mV to reach 100 mA cm–2 and exhibits a Tafel slope of 19 mV dec–1, with stable operation over 350 h and 10,000 CV cycles. In situ Raman spectroscopy, AIMD simulations, and DFT calculations reveal that Os vacancies reorganize interfacial water into an ordered H-bond network, promote O-down water adsorption, and reduce the water dissociation barrier from 1.12 to 0.56 eV. Moreover, an Al | OH– | H2 primary cell using dph-Osdef/o-CNTs as the cathode delivers 1.41 V and 10.92 mW cm–2, enabling simultaneous hydrogen generation and electricity output.
Abstract Pincered transition metal complexes show rich crystal structures owing to intra- and intermolecular hydrogen bonding. Their structural diversity also motivates us to investigate their magnetic interactions mediated by hydrogen bonding. In this study, we report the structural and magnetic properties of copper mononuclear complexes 2FH-CuCl2·H2O and 3F-CuCl2·H2O, with a fluorinated pincered ligand. Both compounds are composed of a uniform chain of molecules coupled by O–H···Cl classical and improper hydrogen-bonding interactions. These compounds exhibit a structural transition induced by orientation ordering of water molecules, which drives bond alternation. The bond alternation also induces dimerization in magnetic interactions between nearest-neighbor Cu ions, evidenced by the magnetization following the isolated antiferromagnetic spin dimer model.
Abstract The stoichiometric and catalytic hydrogenation of nitrous oxide mediated by gas/solid reactions of rhodium(II) pincer complexes [Rh(PNP-tBu)X]+ (X = CH3, H, OH; PNP-tBu = 2,6-(tBu2PCH2)2C5H3N) is reported. A reaction sequence involving Rh(II)–CH3 → Rh(II)–H → Rh(II)–OH → Rh(II)–H bond interconversions has been structurally mapped out by single-crystal X-ray diffraction and verified by EPR spectroscopy. These rhodium(II) metalloradicals are sufficiently robust to catalyze the hydrogenation of nitrous oxide at room temperature with modest productivity (8.3 apparent turnovers). The relative rates of the stoichiometric transformations suggest that Rh–O bond hydrogenolysis is turnover-limiting.
Abstract Metal-ion-assisted Schiff-base condensation enabled the isolation of the complex [Dy(LN6prop)(CH3COO)2](BPh4) (1), which undergoes a ligand exchange reaction with triphenylsilanolate to yield [Dy(LN6prop)(CH3COO)(OSiPh3)](BPh4)·0.5CH2Cl2 (2·0.5CH2Cl2). The crystal structure of 2·0.5CH2Cl2 reveals that the Dy3+ ion is coordinated in an N6O3 environment, adopting a distorted capped square antiprism geometry. 2·0.5CH2Cl2 is a single ion magnet, exhibiting magnetic relaxation in the 2–22 K range with an energy barrier of 465 K, consistent with ab initio calculations and luminescent measurements. 2·0.5CH2Cl2 also functions as a luminescent thermometer with maximum sensitivity SrΔ of 1% K–1 at 12 K. In addition, 2·0.5CH2Cl2 also shows magneto-thermometry, based on magnetic relaxation time (τ) and inverse magnetic susceptibility (1/χ). This magneto-thermometer achieves relatively high magneto-thermal sensitivities (Smax) of 9.3 % K–1 (Sr1/χ) at 10 K and 20 % K–1 (Srτ) at 9 K, while both Sr parameters remain well above 1% K–1 across the entire single-molecule magnet (SMM) operating range. Overall, 2·0.5CH2Cl2 constitutes a bifunctional molecular material, integrating SMM behavior with efficient dual-mode luminescent and magnetic thermometry.
Abstract 2D covalent organic frameworks (COFs) are emerging advanced functional nanomaterials, and metal substrates play a significant role in their synthesis and practical applications by forming Schottky junctions. Nevertheless, detailed information on how metal substrates influence the electronic characteristics of COFs remains unclear. Herein, density functional theory (DFT) calculations are employed to uncover the modulation mechanism of D–A COF and TP COF induced by Ag(111), Au(111), Cu(111), Pd(111), and Pt(111) substrates. The results reveal that metal substrates (Ag, Au, and Cu) regulate the energy-level alignment and charge redistribution of COFs mainly through work function mismatch, while preserving their intrinsic semiconducting characteristics. Among them, Ag(111) and Cu(111) induce significant electron transfer into D–A COF, leading to pronounced n-type doping, whereas Au(111) exhibits relatively weak electronic perturbation. In contrast, Pd(111) and Pt(111) strongly hybridize with COFs, resulting in merging the individual COFs and Pd/Pt substrates into a single bulk system, and no Schottky contact exists. Furthermore, a direct correlation between work function mismatch, carrier concentration increments (Δn), and electron injection barriers (EIB) is established. This study offers useful insights for the rational initial design of COF-metal heterojunctions in the synthesis, subsequent structural characterization, as well as their practical application.
