Electrochemical Behavior of Reduced Graphene Oxide Supported Germanium Oxide, Germanium Nitride, and Germanium Phosphide as Lithium-Ion Battery Anodes Obtained from Highly Soluble Germanium Oxide

Abstract

Germanium and germanium-based compounds are widely used in microelectronics, optics, solar cells, and sensors. Recently, germanium and its oxides, nitrides, and phosphides have been studied as active electrode materials in lithium- and sodium-ion battery anodes. Herein, the newly introduced highly soluble germanium oxide (HSGO) was used as a versatile precursor for germanium-based functional materials. In the first stage, a germanium-dioxide-reduced graphene oxide (rGO) composite was obtained by complete precipitation of GeO2 nanoparticles on the GO from an aqueous solution of HSGO and subsequent thermal treatment in argon at low temperature. The composition of the composite, GeO2-rGO (20 to 80 wt.% of crystalline phase), was able to be accurately determined by the HSGO to GO ratio in the initial solution since complete deposition and precipitation were achieved. The chemical activity of germanium dioxide nanoparticles deposited on reduced graphene oxide was shown by conversion to rGO-supported germanium nitride and phosphide phases. The GeP-rGO and Ge3N4-rGO composites with different morphologies were prepared in this study for the first time. As a test case, composite materials with different loadings of GeO2, GeP, and Ge3N4 were evaluated as lithium-ion battery anodes. Reversible conversion–alloying was demonstrated in all cases, and for the low-germanium loading range (20 wt.%), almost theoretical charge capacity based on the germanium content was attained at 100 mA g−1 (i.e., 2595 vs. 2465 mAh g−1 for Ge3N4 and 1790 vs. 1850 mAh g−1 for GeP). The germanium oxide was less efficiently exploited due to its lower conversion reversibility.

Enhancing Cementitious Composites with Functionalized Graphene Oxide-Based Materials: Surface Chemistry and Mechanisms

“…The reduction of GO involves several design factors that need to be considered, including achieving an optimal C/O ratio in the final product, selectively removing specific types of oxygen groups, selecting a suitable green reducing agent, and ensuring the preservation or enhancement of desired physical and chemical properties of GO. These properties encompass mechanical strength, electrical conductivity [ 84 , 85 ], optical properties, and solubility and dispersibility of the resulting nanosheets [ 81 , 86 ]. Various methods have been proposed to decrease the number of oxygen functional groups on the GO surface, including hydrazine solution, plasma methods, and thermal annealing and hydrothermal reduction [ 31 , 86 , 87 ].…”

Structural evolution and electronic properties of cerium doped germanium anionic nanocluster CeGen− (n = 5–17): Theoretical investigation

“…For instance, they serve as high‐efficiency quantum dots light‐emitting diodes [3], as solar cell photovoltaic power generation film to utilize solar energy [4], and as exceptional catalysts for photocatalysis or electrocatalysis depending on the proper bandgap of materials [5, 6], ultrafast photodetector and highly stable solid‐state batteries [7, 8], etc. Despite the widespread use of silicon‐based materials, germanium offers unprecedented advantages as a substitute for silicon, particularly for high‐mobility charge carriers, a lower band gap to achieve higher saturation velocity and reduced leakage current, which translates into lower drive needed to enhance or maintain devices performance [9–11]. Owing to their significant application in current industrial production, developing novel, suitable, and tunable cluster‐assembled Ge‐based nanomaterials is necessary.…”