Hot Carrier Injection-Driven Nano-Interface Assembly for Hydrogen Generation

Harnessing hot electron transfer (HET) at plasmonic-semiconductor interfaces is a promising route to modulate charge carrier dynamics toward solar energy-driven water splitting for hydrogen generation. Popular semiconductor photocatalysts driving solar-to-hydrogen conversion, such as FeVO₄, suffer from limited visible light absorption, electron-hole recombination, and aqueous instability, often seeking band-gap engineering or cation doping to improve their catalytic prowess. In this first-of-its-kind comprehensive study, we demonstrate a sequentially optimized procedure to obtain one-dimensional (1D) FeVO₄ that is integrated with plasmonic nanoparticles (PNPs) to address these limitations. Anchored on the surface of the semiconductor, PNPs generate hot electrons upon visible light irradiation, that are then transferred to FeVO₄. Finite-difference time-domain simulations verify the electromagnetic field distribution around the FeVO₄-PNP. Additionally, Au, Au-urchin, Ag, and Au+Ag NPs were used to understand the effect of varying sizes, shapes, and plasmonic metals on the photocatalytic efficiency of FeVO₄. Circularly polarized photon-triggered asymmetric hot carrier injection (from Au, Au-urchin, Au+Ag) and plasmon-induced resonance energy transfer (from Ag) reveal voltage-dependent interfacial dynamics that govern charge separation and hydrogen evolution efficiency. The experimental data was used to train a generative reinforcement learning (GRL)-based machine learning model to predict the optimum parameters for tunable band gaps and applied bias photon-to-current efficiency. This study thus lays the foundation for determining appropriate combinations of PNPs and other semiconductor materials for photoelectrochemical (PEC) applications.