Core Viewpoint - The research team from the Institute of Metal Research, Chinese Academy of Sciences, has successfully enhanced the hydrogen production efficiency from solar energy by modifying the photocatalytic material Polytriazine Imide (PTI) through a "lattice engineering" strategy, as published in Nature Communications [1][2]. Group 1 - PTI is recognized for its low cost, environmental friendliness, and suitable band structure, making it a promising candidate for large-scale water splitting for hydrogen production [1]. - The primary challenge with PTI is the tendency of photogenerated charges (electrons and holes) to recombine, which limits its photocatalytic efficiency [1]. - The research involved changing the growth environment of PTI from a lithium and potassium chloride mixed molten salt to a lithium and calcium chloride mixed molten salt, resulting in calcium-doped PTI hexagonal nanodisks [2]. Group 2 - The binding energy between photogenerated electrons and holes in the "excitons" of the calcium-doped PTI was significantly reduced from 48.2 meV to 15.4 meV, which is lower than the thermal disturbance energy at room temperature (25.7 meV) [2]. - This reduction allows for spontaneous dissociation of excitons into free charges under room temperature conditions, enhancing the initial hydrogen production activity by 3.4 times compared to previous PTI photocatalysts [2]. - The findings provide an effective strategy for regulating the photophysical properties of polymer semiconductor photocatalytic materials, promoting their application in various energy conversion scenarios [2].