Effect of single-atom palladium on the anti-toxicity of electrocatalytic reduction removal of nitrate-nitrogen

The enhancement of palladium-based catalysts’ resistance to sulfide toxicity was pursued through the synthesis of six catalysts, namely PdCu MOF₁₀₀₀, Pd MOF₁₀₀₀, Cu MOF₁₀₀₀, PdCu MOF₅₀₀, Pd MOF₅₀₀, and Cu MOF₅₀₀, employing a hydrothermal method. The study delved into the catalytic reduction capabilities of these six catalysts with respect to nitrate (NO₃-N), alongside exploring the impact of sodium sulfite on the catalytic activities of PdCu MOF₁₀₀₀, Pd MOF₁₀₀₀, and Cu MOF₁₀₀₀. Notably, at a NO₃-N concentration of 50 mg/L, significant removal efficacy was observed for PdCu MOF₁₀₀₀, Pd MOF₁₀₀₀, and Cu MOF₁₀₀₀, with PdCu MOF₁₀₀₀ exhibiting a high nitrate removal rate of 97.8 %. Upon the addition of 200 μM sodium sulfite to the system, the removal efficiency of PdCu MOF₁₀₀₀ was still high at 93.3 %, while a reduction in the removal rate of NO₃-N by Pd MOF₁₀₀₀ was observed. Quenching experiments confirmed the presence of hydrogen radicals (H*) in the reaction system, thereby facilitating the indirect-electrocatalytic reduction of nitrate. This observation suggests that catalysts containing Pd single atoms show promise in enhancing their resilience to sulfide toxicity.