Electrochemical hydrogen pumps powered by <i>in situ</i> waste heat recovery and enhanced by 3D MXene-CNT carriers

Abstract

Electrochemical hydrogen pump (EHP) technology is promising for purifying industrial by-product hydrogen (IBH), but low cost and high efficiency are key for practical use. This study recovers low-temperature waste heat from IBH to power the EHP and constructs a high-surface-area support [3D MXene-carbon nanotube (CNT)] to boost the reaction rate. The wrinkled structure inhibits MXene stacking, increases specific surface area to 213.5 m2 g−1, and CNTs form an efficient conductive network. Applied to both EHP and a thermally regenerative battery (TRB), Pt-3D MXene-CNT exhibits a large electrochemically active area and low overpotential. At 1 V, the EHP achieves a current density of 1.12 A cm−2 (93.1% higher than Pt/C) and low decay over 80 h. In the TRB, 3D MXene-CNT-S delivers a peak power density of 86.6 W m−2 and 89.6% capacity retention after 30 cycles. A coupled TRB-driven EHP system is demonstrated, showing a higher H2 production rate and longer operation time. This work provides theoretical guidance for efficient, low-cost IBH purification.