Manipulating the Morphology and Electronic State of\na Two-Dimensional Coordination Polymer as a Hydrogen Evolution Cocatalyst\nEnhances Photocatalytic Overall Water Splitting

Abstract

To\nachieve efficacious photocatalytic overall water splitting,\nsurface modification of photocatalysts with proficient cocatalysts\nfor hydrogen evolution reaction (HER) is imperative. NiBHT, a conductive\ntwo-dimensional coordination polymer (2D CP), or a 2D metal–organic framework (2D MOF), endowed\nwith remarkable chemical stability and HER selectivity, emerged as\na promising candidate for an HER cocatalyst. However, the bulky morphology\nof NiBHT hampered its performance. Here, we demonstrate a strategy\nto miniaturize NiBHT by incorporating the benzene-1,2-dithiol (BDT)\nligand, yielding NiBHT nanoparticles (NiBHT-NP). Beyond morphology,\nempirical evidence unveiled alterations in the electronic state and\ncatalytic activity of NiBHT-NP, and the ramifications of BDT modulation\non intrinsic characteristics are elucidated through density functional\ntheory (DFT) calculations. As a model system, CoO_<i>x</i>/SrTiO₃:Al photocatalyst with NiBHT-NP modification\nexhibited an apparent quantum efficiency (AQE) of 10.3% at 365 nm\nfor overall water splitting. This pioneering work showcases that a\nmodulator ligand may manipulate the morphology, electronic state,\nand catalytic behavior of 2D CPs, holding prodigious potential for\ndeveloping more effective CP-based HER\ncocatalysts.