Thermoelectric Assisted Cascaded Microreactor for Solar Hydrogen Production Using Ti ₃ C ₂ ‐CdS Heterostructure Photoelectrocatalysis

ABSTRACT Harnessing the full solar spectrum for sustainable hydrogen production remains a major challenge in photoelectrocatalytic (PEC) water splitting. Herein, we present a cascaded microfluidic PEC reactor integrated with a thermoelectric generator (TEG), achieving a Solar‐to‐Hydrogen (STH) conversion efficiency of 28%. The device combines three synergistic elements: (i) Ti 3 C 2 ‐CdS heterostructure catalysts that enhance charge separation and suppress recombination; (ii) a planar microfluidic reactor that ensures uniform light penetration, laminar flow, and efficient mass transport; and (iii) a Bi 2 Te 3 ‐based TEG module that harvests solar waste heat to provide supplemental bias for overcoming kinetic barriers. The cascaded architecture enables sequential light harvesting across four reactors, leading to cumulative hydrogen yields exceeding 10 890 µmol g −1 h −1 , while simultaneously enabling rapid water treatment. This work establishes a scalable, self‐powered, and multifunctional platform for decentralized clean energy generation and water purification by integrating thermal‐electrics and PEC pathways into a single compact device.