Gamal Sarah, Khedr Ghada E, Nashaat M, Salah Lobna M, Maarouf Ahmed A, Allam Nageh K
Department of Physics, Faculty of Science, Cairo University, Cairo, 12613, Egypt.
Department of Analysis and Evaluation, Egyptian Petroleum Research Institute, Cairo, 11727, Egypt.
Sci Rep. 2025 Jul 20;15(1):26329. doi: 10.1038/s41598-025-11711-6.
Nitrogen-passivated germanium carbide (GeC) nanomeshes have been systematically investigated as efficient photocatalysts for water splitting. The nanomesh, characterized by a lattice constant of 19.3 Å and a pore diameter of 7.3 Å, maintains a planar architecture with optimized N-Ge and N-C bond lengths of 1.8 Å and 1.3 Å, respectively. Partial density of states (PDOS) analysis indicates that the conduction band is predominantly governed by Ge states, while C states dominate the valence band. Nitrogen incorporation critically alters the electronic structure near the band edges, significantly influencing photocatalytic behavior. Notably, introducing porosity reduces the bandgap from 2.04 eV (pristine GeC) to 1.33 eV in the N-passivated configuration. The calculated band edge positions straddle the redox potentials of water, indicating thermodynamic feasibility for overall water splitting. Several favorable sites were identified for the hydrogen evolution reaction (HER), with nearly thermoneutral ΔG values, suggesting high catalytic efficiency. For the oxygen evolution reaction (OER), the formation of OH* was determined to be the rate-limiting step with a ΔG = 1.84 eV. Bader charge analysis confirmed electron transfer from the OH* species to the adjacent Ge atom, resulting in a net gain of 0.39 |e| by Ge. These findings demonstrate that N-passivated GeC nanomeshes exhibit a favorable electronic structure and catalytic surface characteristics for photocatalytic water splitting.
氮钝化碳化锗（GeC）纳米网已被系统地研究作为用于水分解的高效光催化剂。该纳米网的晶格常数为19.3 Å，孔径为7.3 Å，保持平面结构，优化后的N-Ge键长和N-C键长分别为1.8 Å和1.3 Å。态密度（PDOS）分析表明，导带主要由Ge态主导，而价带由C态主导。氮的掺入严重改变了带边附近的电子结构，显著影响光催化行为。值得注意的是，引入孔隙率将带隙从2.04 eV（原始GeC）降低到氮钝化构型中的1.33 eV。计算得到的带边位置跨越了水的氧化还原电位，表明整体水分解在热力学上是可行的。确定了几个有利于析氢反应（HER）的位点，其ΔG值接近热中性，表明催化效率高。对于析氧反应（OER），确定OH的形成是速率限制步骤，ΔG = 1.84 eV。Bader电荷分析证实电子从OH物种转移到相邻的Ge原子，导致Ge净获得0.39 |e|。这些发现表明，氮钝化的GeC纳米网在光催化水分解方面表现出良好的电子结构和催化表面特性。
