Protophilic TiOx/Ti3C2Tz Nanosheets for Hyper-Efficient Closed-Loop Pd Recycling

Abstract

Sustainable recovery and upcycling/recycling of palladium (Pd) remain critical challenges for industrial competitiveness and environmental protection. However, conventional adsorbents struggle to provide efficient solutions due to their limited performance across diverse pH conditions. Herein, protophilic is presented TiOx/Ti3C2Tz nanosheets (NSs) engineered by incorporating unsaturated titanium oxide (TiOx) nanoclusters, which revolutionize Pd recovery through a unique adsorption-redox mechanism. The TiOx/Ti3C2Tz NSs exhibit a high maximum Pd(II) adsorption capacity of 1983.3 mg g-1 and achieve approximate to 100% recovery efficiency even at ultra-trace concentrations of 100 mu g L-1. Their exceptional protophilicity and strong reducing capability ensure selective Pd(II) reduction to Pd(0) over a wide pH range, followed by fusion-induced precipitation into large particles that are easily separable by filtration. The NSs retain over 98.7% of their performance after a regeneration cycle, confirming excellent structural stability and reusability. Notably, Pd-loaded NSs function as efficient electrocatalysts for hydrogen evolution, achieving a low overpotential of 39 mV at -10 mA cm-2 and a mass activity of 0.19 A mg-1, comparable to commercial Pd/C catalysts. This breakthrough establishes a new paradigm for sustainable precious metal recovery, strengthening global resource security and advancing the circular economy.