Morphology‐Mediated Effective Spatial Charge Separation for High‐Efficiency Photoelectrochemical Hydrogen Production

Abstract Engineering the morphology of quantum dots (QDs) is a pivotal strategy for enhancing the photoelectrochemical (PEC) hydrogen production efficiency by manipulating charge distribution. Still, it remains challenging due to the lack of precise synthesis methods. This work introduces a thermally modulated synthesis protocol that enables precise control over the shell morphology of core–shell QDs. By varying the shell‐growth temperature during the successive ionic layer adsorption and reaction (SILAR) process, two distinct configurations: pyramid‐shaped (CS‐pyr) and spherical‐shaped (CS‐sph) QDs are fabricated. Both types comprise the same CdSe cores with a gradient Cd _x Zn _1‐x Se shell. When integrated into photoanodes, the CS‐pyr QDs‐based photoanode exhibits a significantly enhanced photocurrent density ( J _ph , 23.2 mA cm ⁻² ) in comparison with CS‐sph QDs‐based photoanode (16.6 mA cm ⁻² ), which is also among the most efficient QDs‐based PEC systems. Comprehensive experimental and theoretical analyses reveal that the pyramidal geometry of the CS‐pyr QDs induces an asymmetric distribution of photo‐generated electrons and holes, leading to enhanced charge separation and transfer efficiency. These findings underscore the potential of morphology control as a powerful strategy for optimizing carrier dynamics, laying the groundwork for the design of advanced photoelectronic materials.