Strategic Design of a Single-Source Precursor for in Situ Generation and Integration of Adherent Species on Ni3S4 Entangled-Nanosheets for Energy Storage Applications

Abstract

Synthesizing transition-metal chalcogenides (TMC) via a single-source precursor (SSP) route has shown great potential due to better reproducibility and control over stoichiometry, phase, and morphology. While the SSP converts into TMC, surfactants or coordinating species are essential to ensure dispersibility for further solution-based processing protocols. These additional species are typically highly toxic, difficult to remove, and adversely affect device performance. Here, as a proof of concept, design-induced in situ stabilized Ni₃S₄ (DiSNi) protocol demonstrates that strategic SSP design and optimized reaction conditions can facilitate directed chemical reactivity, gradually generating adhering species, which seamlessly integrate onto the metal chalcogenides, aiding the formation of stable dispersions without utilizing additional stabilizers. The proposed mechanism is validated by detailed strategic experiments and analysis, like X-ray photoelectron spectroscopy (XPS), accelerated dispersion stability measurements, and postsynthesis base treatment, which confirm the presence of in situ generated diethylammonium ion (DEA⁺) as the adherent and corroborate its role in dispersibility. The obtained Ni₃S₄ entangled-nanosheets are utilized to fabricate additive-free symmetric supercapacitors with organic electrolyte for charge storage over an extended potential window of 2.8 V and an energy density of 12.44 μW h cm^–2 at a power density of 0.42 mW cm^–2. The devised DiSNi protocol showcases the importance of the SSP design for achieving multifunctionality. It is anticipated to have a broader impact on the role of careful design of SSP, making it an ideal contender for synthesizing transition-metal chalcogenides.