The present disclosure relates to a method for preparing an ordered porous carbon materials with inexpensive carbon black. The method comprises: dispersing carbon black into a concentrated nitric acid to obtain a uniform dispersion; placing the dispersion in a reactor to perform a reaction by a one-step hydrothermal process; and washing and drying the reaction mixture to obtain an ordered porous carbon material in a honeycomb-like arrangement and rich in oxygen defects. The present disclosure also relates to an ordered porous carbon material prepared by the method, a method for electrocatalytically reducing carbon dioxide to formic acid under ambient temperature and atmospheric pressure by using the ordered porous carbon material, and a method for electrocatalytically reducing nitrogen to ammonia under ambient temperature and atmospheric pressure by using the ordered porous carbon material as a supported catalyst.