Semiconductor-Sensitized thermal cells (STCs) are a novel class of thermoelectric devices capable of utilizing low‑temperature heat (<200 °C) for power generation. An important advantage of the STC is its ability to recover cell performance after discharge when left in a heat source, allowing the cell to extend its lifetime and increase overall power generation. In these systems, thermally excited charge carriers drive redox reactions within the electrolyte, forming a circuit and producing electricity. Because the semiconductor-electrolyte interface governs charge transfer, which is often a dominant bottleneck to cell performance, surface chemistry is a key factor for overall efficiency and stability. Germanium, with its narrow band gap and thermal stability, has emerged as a promising semiconductor for STCs. However, exposure to air readily forms a GeO2 layer that modifies interfacial properties and impedes charge transfer. Conventional methods for GeO₂ removal typically employ hydrofluoric acid (HF) etching; however, its extreme toxicity limits practical use. In this study, we compare two alternative strategies for removing GeO2: carbon-assisted sintering and hydrochloric acid (HCl) treatment. Their effectiveness is benchmarked against HF etching and untreated controls. Surface characterization was performed using FTIR, XPS, and TEM to quantify oxide composition and thickness, and working electrodes were subsequently fabricated into STCs to assess electrochemical behavior and device performance. Carbon sintering induced only partial oxide reduction and was less effective than chemical etching. Both HF and HCl nearly eliminated the oxide, with HCl demonstrating comparable or superior removal efficiency while offering substantially improved safety. Electrochemical testing further confirmed that residual oxide layers significantly suppress power generation and long‑term stability. These results highlight the critical role of interfacial oxide chemistry in STC operation and establish HCl treatment as a practical alternative pathway for balancing performance optimization with laboratory safety.