We report a comprehensive theoretical investigation on phosphorus–boron mixed neutral, anionic, and cationic clusters P₂B_n/P₂B_n⁻/P₂B_n⁺ (n = 3–7) with two phosphorus atoms and three to seven boron atoms. We reveal the common character of all the structures (i.e., the phosphorus atoms choose to occupy the peripheral position), whereas the boron atoms tend to be in the central and inside position of the ground state phosphorus—boron mixed clusters at each stoichiometry. Any three atoms preferentially form a stable triangle and grow with zigzag shape in a planar network. Interestingly, a series of planar motifs (including tetra-, penta-, and hexa-coordination) have been discovered in the phosphorus–boron clusters. The large binding energies (3.6 to 4.6 eV/atom) and quite large HOMO–LUMO gaps (5 to 10 eV) indicate the high stability of the clusters. The energy differences Δ₁E, Δ₂E, and energy gaps display oscillating behavior with increasing numbers of boron atoms. The electron affinity (EA) and ionization potential (IP) generally have small variations, with the EA values ranging from 2 to 3 eV, and the IP values ranging from 7 to 9 eV. Chemical bond analysis shows that the existence of multi-center delocalized bonds stabilize the clusters.

This paper reports the computational study of phosphorus-doped boron clusters PB_n/${\mathrm{P}\mathrm{B}}_{\mathrm{n}}^{–}$/${\mathrm{P}\mathrm{B}}_{\mathrm{n}}^{+}$ (n = 4–8). First, a global search and optimization of these clusters were performed to determine the stable structures. We used density functional theory (DFT) methods and ab initio calculations to study the stability of the atomic clusters and to explore the arrangement of stable structures. We found that the lowest energy structures of the smaller phosphorus-doped boron clusters tend to form planar or quasi-planar structures. As additional boron atoms are added to the smallest structures, the boron atoms expand in a zigzag arrangement or in a net-like manner, and the phosphorus atom is arranged on the periphery. For larger structures with seven or eight boron atoms, an unusual umbrella-like structure appears. We calculated the binding energy as well as other energies to study cluster stability. We calculated the ionization energy, electron affinity, and the HOMO–LUMO gaps. In addition, we used the adaptive natural density partitioning program to perform bond analysis so that we have a comprehensive understanding of the bonding. In order to have a suitable connection with the experiment, we simulated the infrared and photoelectron spectra.

Highly crystalline, hydrophilic and visible-light responsible molecular semiconductor materials are promising photocatalysts for water splitting to produce green hydrogen. However, hydrophobic nature, instability, high cost and the tedious synthesis process of most of the reported organic photocatalysts limit their photocatalytic activity and hinder their scalable applications. Herein, we report stable and easy-to-synthesize sulfone-functionalized molecular single crystals (FSOCA) as efficient hydrophilic photocatalyst for hydrogen evolution reaction. Its structure was determined by 3D electron diffraction technique with atomic resolution. The introduction of the sulfone groups favors the decrease of exciton binding energy, resulting in better exciton separation ability. FSOCA is highly hydrophilic in nature enabling it to efficiently drive sacrificial hydrogen evolution (760 µmol h−1; 76 mmol g−1 h−1). Interestingly, FSOCA remains stable in photocatalytic process for at least 400 hours showing negligible structure change, has and can cumulatively produce 179.2 mmol (about 4 L) of hydrogen. Employing transient spectroscopy, we find that the highly coplanar structure greatly enhances the transport of charge carriers to hole scavengers. In-situ Fourier transform infrared spectroscopy and DFT calculation shows that hydrogen bonding between sacrificial agent (ascorbic acid) with sulfone group is energetically favorable for the adsorption of ascorbic acid on FSOCA, thereby significantly improving the oxidation reaction kinetics and the photocatalytic performance. This work provides a scalable, efficient and low-cost strategy to synthesize highly active and stable organic photocatalysts, which can potentially be applicable in scalable photocatalysis.