A Simple Ni‐based Metal–organic Framework as Catalyst for Dye‐sensitized Photocatalytic H₂ Evolution from Water Reduction

Abstract

Metal–organic frameworks (MOF) are recently developed coordination porous materials, and their unique structures are very conducive to catalytic reactions. In this paper, p‐benzenedicarboxylic acid (PBA)‐Ni2+ MOF materials (denoted as PBA‐Ni‐x, where x represents the initial ratio of PBA to Ni2+) were synthesized by a hydrothermal method and characterized by X‐ray diffraction (XRD), Fourier transform infrared spectra (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and N2 gas adsorption. H2 gas was produced using the synthesized MOF as a photocatalyst and Eosin Y as a photosensitizer. The dependence of the special surface area and thickness of the nanosheets of Ni‐MOF on the initial ratio of PBA to Ni2+ (PBA/Ni2+) was investigated. The BET surface areas of PBA‐Ni‐1 PBA‐Ni‐2 and PBA‐Ni‐3 are 11.00, 24.61 and 13.04 m2 g−1, respectively. And the thicknesses of nanosheets are approximately 600–1000, 200–500 and 300–700 nm. Among the three materials, PBA‐Ni‐2 has the thinnest sheet‐like structure and largest surface area. Thus, it displays the highest H2 evolution rate of 20.0 μmol h−1. The noble‐metal‐free hydrogen production system is valuable for the application of MOF materials in photocatalytic water splitting.

Piezocatalytic Effect Induced Hydrogen Production from Water over Non-noble Metal Ni Deposited Ultralong GaN Nanowires

“…Obviously, the Ni 2p 3/2 peak located at 852.6 eV, which belongs to Ni metal in the as-prepared Ni/GaN, was shifted to 855.4 eV (Figure c) after the piezocatalytic test, which indicates that the Ni metal has been partially oxidized. , The XPS survey spectra of Ni/GaN-1, Ga 2p, N 1s, and O 1s before and after the H 2 production reaction are displayed in Figure S7. Ni/NiO serves as highly reactive sites for the hydrogen evolution reactions (HERs) due to the suitable band structure that lowers the reaction barriers, − which is responsible for the stable cycling piezocatalytic activity.…”

Carbon nitride quantum dots‐modified cobalt phosphate for enhanced photocatalytic H2 evolution

“…EY, as a usual xanthene dye with electronic donoracceptor (D-A) structure, was proved to be an effective sensitizer for photocatalytic H 2 evolution by many previous works. 8,10,20 Unlike a typical photosensitized system, it is commonly believed that the direct electron transfer from the excited EY to catalysts is forbidden. In primary photochemical stage, EY absorbs visible-light photo to yield singlet excited 1 main reaction paths: (I) transfer electron to photocatalyst and reduce H + .…”

“…Xanthenes, such as eosin Y (EY), are excellent photosensitizers with great promise for hydrogen production from water splitting because of their inexpensiveness, high quantum yield of triplet states and proper redox abilities. [8][9][10][11] In current studies, Pt and its compounds are still the best representative for HER catalysts. It is of critical significance to develop economic systems without noble metals.…”

“…A molecular catalytic system commonly composes of a photosensitizer, a catalyst for hydrogen evolution reaction (HER) and an electron donor (ED). Xanthenes, such as eosin Y (EY), are excellent photosensitizers with great promise for hydrogen production from water splitting because of their inexpensiveness, high quantum yield of triplet states and proper redox abilities 8–11 …”

Band Gap Modulation in Fluorescein-Based Isostructural Coordination Polymers for Enhanced Photocatalytic Hydrogen Evolution under Visible Light

“…Du and co-workers analyzed the effects of pH values, the sacrificial agent, and the photosensitizer for photocatalytic hydrogen production in detail with a water-stable Ni­(II)-based layered MOF [Ni 2 (PymS) 4 ] n (PymSH = Pyrimidine-2-thio) in the presence of fluorescein as a photosensitizer and TEA as a sacrificial agent . It is evident from the studies that along with the highly ordered coordination polymeric network of metal and ligand, the sensitizers like eosin Y, rose Bengal, rhodamine B, and fluorescein are crucial to drive the photocatalytic reaction. − However, the homogeneous nature of these dyes results in low stability due to their dissolution and self-degradation under photocatalytic reaction conditions in water. There are very rare instances where such dye molecules are part of the framework itself. − Out of these, only one example is reported for the HER, where an eosin Y-based MOF exhibited efficient photocatalytic activity for H 2 evolution from EtOH–water solvent under visible-light irradiation with a turnover number of 13,920 .…”