The disclosure concerns reactors for reducing metal oxide particles comprising: (a) a vertical heated channel; (b) a plurality of inclined, vertically stacked metal meshes, said meshes comprising: (i) a particle opaque portion comprising over about 50% of the meshes' length and having openings smaller than the smallest particle; and (ii) a particle transparent portion having openings large enough for particles to pass to the next level; (c) a vibration motor coupled to the meshes; and (d) an insulated chamber for storing the particles. Other aspects of the disclosure concern methods of reducing metal oxide particles. Yet other aspects concern thermochemical energy storage reactor devices comprising such reactors.