Coupling thermoelectricity and electrocatalysis for hydrogen production via PbTe PbS/TiO 2 heterojunction

Abstract PbTe PbS/TiO 2 electrodes are produced via wet chemical routes for splitting water into hydrogen at the ambient temperatures. PbTe nano-crystals are firstly deposited via the successive ionic layer adsorption and reaction (SILAR) treatment onto TiO 2 nanotube arrays (TNAs) prepared by anodic oxidation of Ti substrates. Subsequently, linear sweep voltammetry (LSV) is employed to convert the outer PbTe into PbS, producing PbTe PbS/TiO 2 electrodes with a gradient p-n-n band configuration. With the external electric field, the vector charge transfer effect of the TNAs and the gradient energy band structure of PbTe PbS/TNAs, the two electrode system in which PbTe PbS/TNAs functions as the anode illustrates excellent hydrogen production activities. The whole electrochemical system consisted of anode, cathode, electrolyte serves as a hot side while the endothermic electrochemical reactions in hydrogen production as an in situ cold side. At 70 °C and 1.0 V bath voltage, the system registers 6.1 mL cm −2  h −1 rate of hydrogen generation, consuming electric power of 26.2 kW h kg −1 H 2 , with an energy efficiency of 88.5% and a heat efficiency of 49.9%. This method demonstrates a novel pathway to produce chemical energy from low quality waste heat, benefitting from thermoelectric and electrocatalytic coupling.