Binary Ni₂P/Ti₃C₂ Multilayer Cocatalyst Anchored TiO₂ Nanocomposite with Etchant/Oxidation Grown TiO₂ NPs for Enhancing Photocatalytic H₂ Production

Abstract

Ternary nickel phosphide (Ni2P) and titanium carbide (Ti2C2) MXene supported titanium dioxide nanoparticles (TiO2 NPs) to construct a Ni2P/TiO2 NPs/Ti3C2 MXene hybrid composite for stimulating photocatalytic hydrogen production has been investigated. The performance comparison of two-dimensional (2D) Ti3C2 MXene multilayers with in situ grown TiO2 NPs synthesized through etching and atmospheric calcination methods was conducted and promising separation of charge carriers was observed. TiO2 NPs embedded over 2D Ti3C2, synthesized through both methods, were found to have promise in promoting photoactivity, whereas 2.89 times more H2 yield was attained with TiO2 NPs embedded through the oxidation (ox) approach. Using the Ni2P/TiO2/Ti3C2-ox heterostructure, a rate of 9425 ppm g–1 h–1 of H2 was reached, 2.77, 4.81, and 8.28 times more than those using Ni2P/TiO2, TiO2/Ti3C2 and TiO2 samples, respectively. This obviously augmented H2 production rate can be ascribed to a binary cocatalyst with efficient charge carrier separation, higher light absorption, and more attachment of water molecules. Among different alcohols, glycerol was a promising reagent to yield more hydrogen in addition to having higher photostability in consecutive cycles. This study provides a new approach to construct a ternary nanocomposite with proficient charge carrier separation and would be beneficial for other energy applications.

Ni2P nanowire arrays grown on Ni foam as an efficient monolithic cocatalyst for visible light dye-sensitized H2 evolution

“…In addition, because there is only a thin layer of Ni 2 P formed on the surface of NF, thus Ni 2 P NL/NF is prone to be oxidized when exposed to air. In contrast to Ni 2 P NL/NF, for Ni 2 P NWAs/NF-15-160, the intensity of the Ni 2p 3/2 (Ni 2p 1/2 ) peak at 852.9 eV (870.2 eV) for Ni–P species substantially enhanced due to the effective phosphorization of the preformed Ni oxide/hydroxide layer, 31,32 resulting in the formation of high-density Ni 2 P NWAs. The content of P on NF for Ni 2 P NWAs/NF-15-160 is determined to be as high as 3.43 wt% by inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis, corresponding to a loading amount of 16.5% for the Ni 2 P NWAs grown on a NF substrate.…”

“…3d shows the high resolution XPS spectra of the P 2p core level of Ni 2 P NL/NF and Ni 2 P NWAs/NF-15-160. The P 2p region of Ni 2 P NL/NF exhibits two peaks at 129.9 and 131.1 eV corresponding to a doublet P 2p 3/2 and P 2p 1/2 of Ni–P species, 30–32 respectively, along with two intense peaks at 133.9 and 134.4 eV, ascribed to the P–O species. Similar to the Ni 2 P NL/NF, the fitting of the P 2p region of Ni 2 P NWAs/NF-15-160 also indicates the existence of both Ni–P (P 2p 3/2 : 129.6 eV; P 2p 1/2 : 130.6 eV) and P–O (P 2p 3/2 : 133.0 eV; P 2p 1/2 : 134.1 eV) species.…”

“…3d shows the high resolution XPS spectra of the P 2p core level of Ni 2 P NL/NF and Ni 2 P NWAs/NF-15-160. The P 2p region of Ni 2 P NL/NF exhibits two peaks at 129.9 and 131.1 eV corresponding to a doublet P 2p 3/2 and P 2p 1/2 of Ni-P species, [30][31][32] respectively, along with two intense peaks at 133.9 and 134.4 eV, ascribed to the P-O S1, † although the HER activity of the Ni 2 P NWAs/NF monolithic cocatalyst in the ErB-TEOA system is not impressive compared to the powdery Ni 2 P-loaded photocatalysts employing metal sulfides (CdS and CdZnS) as light harvesters, its activity is comparable to or even higher than those of the Ni 2 P-loaded metal-free g-C 3 N 4 photocatalysts. Given that the used ErB is a metal-free photosensitizer that has limited light absorption ability similar to g-C 3 N 4 , it would be expected that if inorganic semiconductors with good light absorption capacity are used as light harvesters, the HER activity of the Ni 2 P NWAs/NF monolithic cocatalyst could be substantially enhanced.…”

“…Among them, Ni 2 P and its composites with conductive carbons and other metal phosphides have exhibited much superior catalytic HER activity. [30][31][32] However, these transition-metal-based cocatalysts are generally loaded on semiconductor-based photocatalysts or directly dispersed in molecular systems, typically leading to insufficient HER activity due to the interference to light absorption and inferior stability because of easy detachment from the semiconductor surface or inevitable aggregation in molecular systems, and making recovery difficult due to their own powdery forms, which seriously hinder their practical application for long-term and large-scale photocatalytic HERs.…”

NixP and Mn3O4 dual co-catalysts separately deposited on a g-C3N4/red phosphorus hybrid photocatalyst for an efficient hydrogen evolution

“…15 For reductive co-catalysts, advances have been made by loading different transition metal phosphides as the co-catalysts for HERs. 24,25 Recently, Tasleem et al prepared a TiO 2 /Ni 2 P/Ti 3 AlC 2 composite, where the role of Ni 2 P was systematically studied by adjusting the loading ratio, irradiation time and so on. Ni 2 P as the co-catalyst has also enhanced the HER rate compared with that of the TiO 2 /Ti 3 AlC 2 composite.…”