Unraveling Electron Structure and Reaction Mechanisms of Functionalized Nickel-Based Complexes for Efficient Hydrogen Evolution

Abstract

Developing an advanced photocatalytic watersplitting system for hydrogen evolution reaction (HER) remains a challenge. Herein, a series of easily available pyridine-functionalized nickel-based photocatalysts with elaborate electronic structures were predicted by density functional theory (DFT). The results indicated that the migration of photoinduced electrons could be significantly improved after functionalization of the photocatalysts, leading to a high performance for HER. Under the optimized conditions, as high as 1613.51 μmol of H 2 can be produced over 25 mg of Ni(dpi)(pys) 2 (dpi = 2,2′-dipyridyl) (pys = 2-mercaptopyridine) (PNSP 1) after irradiation for 3 h, corresponding to a turnover number (TON) of 5470. The reaction mechanism was further explored by experimental and DFT calculation results. The outstanding HER performance is primarily associated with a high photoelectron transfer rate, a weak binding energy between the photocatalyst and hydrogen molecules, and enhanced active sites for HER, which might benefit the reduction of the energy barrier of HER intermediates, ultimately boosting the performance for HER. This report on the use of DFT to predict molecular complexes with high-efficiency catalytic properties affords significant insights for the design of new and inexpensive photocatalysts.

Amorphous NxC Coating Promotes Electrochemical CO2 Deep Reduction to Hydrocarbons over Ag Nanocatalysts

“…45% at −1.5 V (vs RHE), indicating that N x C could advance the HER kinetics of Ag NPs. As per previous reports, the N species could activate H 2 O to promote the HER performance. − Figure b presents the CO FE over the series catalyst, and as high as 98% CO is generated over Ag NPs within the applied potential range. While the generation rate of CO decreases sharply with the increase of the N x C layer thickness, only less than about 30% CO are produced at −1.4 V (vs RHE) over the Ag@N x C-2 catalyst.…”

Accelerating Nickel-Based Molecular Construction via DFT Guidance for Advanced Photocatalytic Hydrogen Production

“…The calculated electrostatic potentials of NQP 1–3 are shown in Figure . Generally, there is a low electrostatic potential in the blue part, where electrophilic reactions occur easily . This implies that the electrophilic reactions of NQP 1–3 take place in the Ni, S, and N atoms nearby.…”

“…1 H and 13 C spectra were collected on a Bruker DRX 600 spectrophotometer in deuterated reagent, and chemical shifts are referenced to residual solvent. Electrospray ionization mass spectra (ESI-MS), Fourier transform infrared spectroscopy (FT-IR) spectra, UV–vis spectra, photoluminescence (PL) emission spectra, X-ray photoelectron spectroscopy (XPS), Raman spectra, powdered X-ray diffraction (XRD) patterns, elemental analysis (EA), and scanning electron microscopy (SEM) were measured as described previously . Brunauer–Emmett–Teller (BET) surface areas of molecular catalysts were measured on a Micromeritics ASAP 2020 apparatus at 77 K using N 2 adsorption data.…”

“…HCl and NaOH were used to adjust the pH of the system. In addition, the specification of the Xe lamp, the wavelength of the filter, the light intensity, and the standard of the gas chromatography were as described before (ref ). Finally, the amount of hydrogen generation was recorded every 0.5 h. Equation was used to calculate the apparent quantum efficiency (AQE) of H 2 generation around 400 nm.…”

“…The cyclic voltammetry (CV), the photocurrents, and the electrochemical impedance spectra (EIS) were measured using the apparatus described in ref .…”