Influence of sodium precursor on the cubic to monoclinic phase transformation and controlled colloidal synthesis of NaSbS 2 nanoparticles Maria Zubair, Syed Abdul Ahad, Ibrahim Saana Amiinu, Mohini Mishra,
Shalini Singh, Kevin M. Ryan University of Limerick, Ireland
Alkali pnictogen dichalcogenides have been identified as a promising semiconducting material for energy conversion devices. [1,2] However, the controlled nanoscale synthesis and phase controlled synthesis of these ternary compounds remain under developed. [3] Here, the phase controlled synthesis of colloidal NaSbS 2 nanocrystals is reported. We employed the colloidal hot injection approach and explored the influence of a wide range of synthesis parameters (e.g., reaction time and temperature, choice of a sodium precursor, and ligand ratio) on the phase controlled synthesis of NaSbS 2 NCs. We tried to identify “ sweet spots ” in the reaction space that led to phase controlled NaSbS 2 NCs in the size range of 30-50 nm. XRD patterns recorded for aliquots collected at different reaction time interval revealed that NaSbS 2 nucleated in the cubic phase and then transformed to monoclinic phase as the reaction progressed up to 2 h. A very striking observation was that the NPs synthesized using NaOH as a reactant preferred to remain in the cubic phase and did not undergo a phase transformation to the monoclinic phase over 2 h of reaction time. Under similar experimental conditions, NCs prepared using mixture of NaOH:NaOAc exhibited the phase transformation. Thermogravimetry and DSC shows both cubic and monoclinic phase NaSbS 2 NCs undergoes 9-12 % weight loss between 280 to 320 ᵒC, which is likely associated with the loss of surface ligands. FTIR spectroscopy and NMR revealed the coordination of carboxylate and amine functionality to the surface of the NCs. Further NaSbS 2 NCs were firstly tested as anode material for batteries. The NaSbS 2 NCs electrodes delivers a specific capacity of 750 mAh g -1 at a current density of 200 mA g -1 after 100 cycles. References 1. Bush, K. A.; Frohna, K.; Prasanna, R.; Beal, R. E.; Leijtens, T.; Swifter, S. A.; McGehee, M. D. Compositional engineering for efficient wide band gap perovskites with improved stability to photoinduced phase segregation. ACS Energy Letters 2018 , 3 (2), 428-435. 2. Shao, Y.; Fang, Y.; Li, T.; Wang, Q.; Dong, Q.; Deng, Y.; Yuan, Y.; Wei, H.; Wang, M.; Gruverman, A. Grain boundary dominated ion migration in polycrystalline organic–inorganic halide perovskite films. Energy & Environmental Science 2016 , 9 (5), 1752-1759. 3. Tress, W. Metal Halide Perovskites as Mixed Electronic–Ionic Conductors: Challenges and Opportunities From Hysteresis to Memristivity. The journal of physical chemistry letters 2017 , 8 (13), 3106-3114.
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