In today's world, batteries and other electrochemical energy storage technologies are crucial for transitioning from a fossil fuel-based economy to a sustainable one. This has led to a growing demand for energy storage in electric vehicles, portable devices, and grid or plant scale storage. As a result, researchers are focused on developing cleaner and more efficient electrochemical energy conversion systems (Cui et al., 2017; He et al., 2023; Olsson et al., 2021; Tang et al., 2019). One type of power source that is becoming more popular is the alkaline metal-ion battery (AIB), including the Li-ion battery (LIB) (Yao et al., 2022), Na-ion battery (NIB) (C. Xu et al., 2022) dan K-ion battery (KIB) (Kang et al., 2022). These batteries are attracting attention because they have a high power density, excellent cycle performance, and long cycle life. As a result, the development of AIBs is ongoing to meet increasing energy storage demands (He et al., 2023; Olsson et al., 2021; Tang et al., 2019).
The performance of batteries is dependent on the electrode materials used, specifically the anode and cathode. To achieve high performance, optimization of these materials is necessary. Carbonaceous materials, such as graphite, are commonly used as anodes for LIBs but are not suitable for NIBs due to their inability to store large amounts of Na+ (less than 35 mAh g− 1) and have a low reversible capacity of ~ 260 mAh g− 1 in KIB. Graphene materials have shown promising results as NIB anodes and have also demonstrated good performance for LIBs and KIBs (Dou et al., 2019; Jian et al., 2015; Y. Li et al., 2019; Olsson et al., 2021; Stevens & Dahn, 2001; Sun et al., 2021). Graphene, a one-atom-thick layer with a two-dimensional architecture of carbon materials, has received great attention because of its superior electrical, mechanical, and chemical properties (G. Li et al., 2017). More extraordinary, nitrogen-doped graphene (NGr) is becoming increasingly popular due to its high-performance electrochemical properties in comparison to pure graphene. The addition of N atoms in the graphene network creates activated regions where they are next to carbon atoms. Moreover, N atoms can also function as binding sites for metal ions. When combined with other active material, high-quality NGr provides excellent electrical conductivity. Therefore, NGr unique properties make it a highly sought-after material for enhancing electrochemical capabilities in metal oxide matrices (Kamal et al., 2022; Kaur et al., 2018; Miao et al., 2019; Naveenkumar et al., 2023).
To enhance the electrochemical performance of anode materials, we utilize a research strategy that involves incorporating NGr composites with the help of metal oxide nanoparticles. This is achieved through a two-step hydrothermal method. Our approach involves using selected metal oxides such as NiO and TiO2, which are highly effective modifiers with fast and reversible faradaic redox processes. These metal oxides interact with ions and electrons in their charge storage mechanisms, making them ideal for our research objectives (Al Kiey et al., 2022; Tang et al., 2019). NiO is a popular choice for AIB anode material due to its cost-effectiveness, high theoretical capacity, and non-toxicity. However, the anode made of pure NiO particles has poor initial Coulomb efficiency and cycle performance. To improve NiO performance as an anode, several attempts have been made to incorporate nanostructures such as nanoparticles (Natsir et al., 2021; L. Zhang et al., 2016; Y. Zhang et al., 2021). On the other hand, TiO2 is a zero-strain embedding material, which makes it highly reversible, safe, and stable during electrochemical processes. Despite its excellent properties, TiO2 practical development for commercial use is limited due to its low theoretical capacity (Chen et al., 2023; Long et al., 2018; Wang et al., 2021).
The purpose of this study is to analyze the performance of NGr@NiO/TiO2 hollow nanosphere anodes using cyclic voltammetry (CV), which is a fundamental electrochemical analysis technique. This method helps to identify the oxidation or reduction voltage, detect impurities, and ensure that the reaction occurs correctly. The goal is to determine if NGr@NiO/TiO2 hollow nanosphere anodes are suitable as superior anode candidates for AIB (Huang et al., 2019; Kim et al., 2020). Miao et al. (Miao et al., 2019) synthesized a TiO2/N-graphene/Si-MCP composite for LIB with the redox peaks observed in the 2nd and 3rd cycles overlapping each other implying high reversibility and stability. Porous NiO hollow quasi-nanospheres showing the first three CV profiles of the NiO electrode at a voltage of 0–3 V with a scan rate of 0.2mVs − 1 (J. Xu et al., 2017). As a NIB anode, TiO2/NRGO shows four CV profiles at 0.1 mV s − 1 (0.01-3V). An irreversibly reduced peak was observed at 1.2 V during the initial cathodic sweep, which was caused by electrolyte decomposition and SEI formation. Based on this, it is very important to understand the electrochemical properties of NGr@NiO/TiO2 composites with CV so that it becomes the main basis for developing anodes in the future.