A new active species of Pd-Nx synthesized by hard-template method for efficiently catalytic hydrogenation of nitroarenes

•g-C3N4 with more defects was synthesized by hard-template method.•The existence of defects is conducive to the formation of Pd-Nx species on Pd/g-C3N4.•The obtained Pd/g-C3N4 showed better catalytic performance than conventional one.•The role of Pd-Nx species in the catalytic reaction was illustrated.