Amorphization-Induced Cation Exchange in Indium Oxide Nanosheets for CO₂-to-Ethanol Conversion

Cation exchange (CE) in metal oxides under mild conditions remains an imperative yet challenging goal to tailor their composition and enable practical applications. Herein, we first develop an amorphization-induced strategy to achieve room-temperature CE for universally synthesizing single-atom doped In₂O₃ nanosheets (NSs). Density functional theory (DFT) calculations elucidate that the abundant coordination-unsaturated sites present in a-In₂O₃ NSs are instrumental in surmounting the energy barriers of CE reactions. Empirically, a-In₂O₃ NSs as the host materials successfully undergo exchange with unary cations (Cu²⁺, Co²⁺, Mn²⁺, Ni²⁺), binary cations (Co²⁺Mn²⁺, Co²⁺Ni²⁺, Mn²⁺Ni²⁺), and ternary cations (Co²⁺Mn²⁺Ni²⁺). Impressively, high-loading single-atom doped (over 10 atom %) In₂O₃ NSs were obtained. Additionally, Cu/a-In₂O₃ NSs exhibit an excellent ethanol yield (798.7 μmol g^-1 h^-1) with a high selectivity of 99.5% for the CO₂ photoreduction. This work offers a new approach to induce CE reactions in metal oxides under mild conditions and constructs scalable single-atom doped catalysts for critical applications.