Alemdar Sila, Basak Aleyna, Metin Onder
Department of Chemical and Biological Engineering, Graduate School of Sciences and Engineering, Koç University, Sarıyer, 34450 İstanbul, Türkiye.
Department of Chemistry, College of Sciences, Koç University, Sarıyer, 34450 İstanbul, Türkiye.
ACS Appl Mater Interfaces. 2023 Oct 18;15(41):48096-48109. doi: 10.1021/acsami.3c08787. Epub 2023 Oct 8.
Ammonia borane (AB) holds great promise for chemical hydrogen storage, but its slow dehydrogenation kinetics under ambient conditions requires a suitable catalyst to facilitate hydrogen production from AB. Here, we fabricated binary red phosphorus/graphitic carbon nitride (RP/g-CN) heterojunctions decorated with Pt nanoparticles (NPs, denoted Pt/RP/g-CN) with a facile ultrasound-assisted two-step protocol as a photo-assisted catalyst for the hydrolysis of AB (HAB). The heterojunction established through intimate P-O-N bonds was proven to have improved photophysical properties such as a lower electron-hole recombination and enhanced visible light utilization compared to the pristine components. With the incorporation of Pt NPs, the optical properties of RP/g-CN heterojunctions were further improved through Schottky junction formation between semiconductors and Pt NPs, enabling a superb hydrogen gas (H) generation rate of 142 mol H·mol Pt·min under visible light irradiation. Even though g-CN is a well-known host material for many metal NPs, here we discovered that the interaction of Pt NPs with RP in the ternary heterojunction structure is more favorable than that of g-CN, stressing the key role of RP as a support material in the designed ternary heterostructure. The band alignment of the ternary heterojunction catalyst along with the flow of charge carriers was also studied and shown to be a type-II heterojunction structure without hole migration, namely, a complex type-II heterojunction. Several scavenger experiments were also conducted to explain the mechanism of the photo-assisted HAB. To the best of our knowledge, this is the first example of a dual mechanism proposed for the visible light-assisted HAB. While the majority of the H was believed to be produced on the Pt NPs surface with the traditional B-N bond dissociation mechanism, the strong oxidizing action of OH radicals formed by the heterojunction photocatalyst was also speculated to account for the 33% increase in the activity upon visible light irradiation through another mechanism.
氨硼烷（AB）在化学储氢方面具有巨大潜力，但其在环境条件下缓慢的脱氢动力学需要合适的催化剂来促进AB制氢。在此，我们通过简便的超声辅助两步法制备了负载铂纳米颗粒（NPs，记为Pt/RP/g-CN）的二元红磷/石墨相氮化碳（RP/g-CN）异质结，作为光辅助催化剂用于氨硼烷水解（HAB）。通过紧密的P-O-N键形成的异质结被证明具有改善的光物理性质，与原始组分相比，其具有更低的电子-空穴复合率和更高的可见光利用率。随着Pt NPs的引入，RP/g-CN异质结的光学性质通过半导体与Pt NPs之间形成肖特基结而进一步改善，在可见光照射下实现了高达142 μmol H₂·mol⁻¹ Pt⁻¹·min⁻¹的出色氢气（H₂）生成速率。尽管g-CN是许多金属NPs的著名主体材料，但在此我们发现，在三元异质结结构中Pt NPs与RP的相互作用比与g-CN的相互作用更有利，强调了RP作为设计的三元异质结构中载体材料的关键作用。还研究了三元异质结催化剂的能带排列以及电荷载流子的流动，结果表明其为无空穴迁移的II型异质结结构，即复杂的II型异质结。还进行了几项清除剂实验以解释光辅助HAB的机理。据我们所知，这是首次为可见光辅助HAB提出双重机理的实例。虽然大多数H₂被认为是通过传统的B-N键解离机理在Pt NPs表面产生的，但异质结光催化剂形成的OH自由基的强氧化作用也被推测通过另一种机理解释了可见光照射下活性提高33%的原因。
