In　modern　heterogeneous　catalysis,　it　remains　highly　challenging　to　create　stable,　low-cost,　mesoporous　2D　photo-/electro-catalysts　that　carry　atomically　dispersed　active　sites.　In　this　work,　a　general　shape-preserving　amorphous-to-crystalline　transformation　(ACT)　strategy　is　developed　to　dope　various　transition　metal　(TM)　heteroatoms　in　ZrO2,　which　enabled　the　scalable　synthesis　of　TMs/oxide　with　a　mesoporous　2D　structure　and　rich　defects.　During　the　ACT　process,　the　amorphous　MZrO2　nanoparticles　(M　=　Fe,　Ni,　Cu,　Co,　Mn)　are　deposited　within　a　confined　space　created　by　the　NaCl　template,　and　they　transform　to　crystalline　2D　ACT-MZrO2　nanosheets　in　a　shape-preserving　manner.　The　interconnected　crystalline　ACT-MZrO2　nanoparticles　thus　inherit　the　same　structure　as　the　original　MZrO2　precursor.　Owing　to　its　rich　active　sites　on　the　surface　and　abundant　oxygen　vacancies　(OVs),　ACT-CoZrO2　gives　superior　performance　in　catalyzing　the　CO2-to-syngas　conversion　as　demonstrated　by　experiments　and　theoretical　calculations.　The　ACT　chemistry　opens　a　general　route　for　the　scalable　synthesis　of　advanced　catalysts　with　precise　microstructure　by　reconciliating　the　control　of　crystalline　morphologies　and　the　dispersion　of　heteroatoms.