Monodispersed ferric oxide nanoboxes as low-cost catalyst for long-term electrochemical hydrogen generation

•The facilely prepared Fe2O3 nanoboxes are free of agglomeration.•The Fe2O3 nanoboxes exhibit the high stable HER performance in alkaline solution.•Electrochemical surface area dominates the HER performance of Fe2O3 nanoboxes.•Calcination treatment makes the HER performance of the Fe2O3 nanoboxes worse.