Solvent-free elaboration of Ni-doped MnOx catalysts with high performance for NH3-SCR in low and medium temperature zones

•Cryptomelane-type NMOs were synthesized by solvent-free in-situ Ni-doping method.•NMOs-4 catalyst showed over 85 % NO conversion at 100–300 ℃ for NH3-SCR.•Tuning Ni loading could control the surface acidity and redox ability.•NH3 activation was the key to broaden the active temperature region.