A Way for Derived Carbon Materials by Thermal Etching Hybrid Borate for Electrochemical CO₂ Reduction

Two hybridized skeleton borates [Zn(en)₂]·[B₇O₁₂(OH)] (1; en = ethylenediamine) and [Cd(1,3-dap)₂]·[B₅O₈(OH)]·H₂O (2; 1,3-dap = 1,3-diaminopropane) were solvothermally synthesized. The boron oxide clusters formed 2D planes, and these planes formed a 3D structure through co-oxygen links of metal complexes. Herein, a novel strategy has been developed, i.e., the derived guest carbon materials from semi-decomposed borate are incorporated into the void of host borate crystals in situ during the thermal etching process. Moreover, the effect of temperature on fluorescence of derived carbon materials was studied. By controlling the calcining temperature, carbon dots with obvious free radicals can be found via ESR technique. Carbon dots in the ethanol phase exhibited variable photoluminescence. Furthermore, it derived semi-decomposition carbon materials via thermal etching based on compounds 1 and 2. In an hydrogen cell reactor, carbon material Zn-based catalyst 1-200 catalyzes CO₂ reduction to CO with a selectivity that reaches 50.8% at -1.4 V vs RHE.