Related party transactions (Details 1) - USD ($) |
Mar. 31, 2026 |
Sep. 30, 2025 |
|---|---|---|
| Due to related parties | $ 3,892,013 | $ 293,919 |
| Centurynew USA Inc [Member] | ||
| Due to related parties | 3,600,008 | 0 |
| Zhejiang Tantech Bamboo Technology Co., Limited [Member] | ||
| Due to related parties | 64,232 | 52,146 |
| Yefang Zhango [Member] | ||
| Due to related parties | $ 227,773 | $ 241,773 |