Metal-free efficient photocatalyst for stable visible water splitting via a two-electron pathway

Abstract

The use of solar energy to produce molecular hydrogen and oxygen (H2 and O2) from overall water splitting is a promising means of renewable energy storage. In the past 40 years, various inorganic and organic systems have been developed as photocatalysts for water splitting driven by visible light. These photocatalysts, however, still suffer from low quantum efficiency and/or poor stability. We report the design and fabrication of a metal-free carbon nanodot-carbon nitride (C3N4) nanocomposite and demonstrate its impressive performance for photocatalytic solar water splitting. We measured quantum efficiencies of 16% for wavelength λ = 420 ± 20 nanometers, 6.29% for λ = 580 ± 15 nanometers, and 4.42% for λ = 600 ± 10 nanometers, and determined an overall solar energy conversion efficiency of 2.0%. The catalyst comprises low-cost, Earth-abundant, environmentally friendly materials and shows excellent stability.

Modeling, Simulation, and Implementation of Solar‐Driven Water‐Splitting Devices

“…[5c, 59] Two types of particle-based PEC systems, termed a Type 1 reactor for a single-vessel reactor (Figure 4 c1) and a Type 2 reactor for a dual-vessel reactor (Figure 4 c2), have been proposed conceptually and demonstrated experimentally at different levels of device integration. For the Type 1 reactor, single particle systems, including In 1Àx Ni x TaO 4 , [60] (Zn 1+x Ge)(N 2 O x ) solid solution, [61] (Ga 1Àx Zn x )(N 1Àx O x ) solid solution, [62] CoO [63] and C 3 N 4 /C-dots, [64] as well as tandem-particle systems, including SrTiO 3 :Rh//BiVO 4 [65] and nitrogen-doped graphene oxide (NGO) [66] that are electrically connected with a solidstate electron mediator have been investigated. The STH conversion efficiency in the demonstrated and stable Type 1 reactor systems is often low (< 2 %).…”

Modelling materials for solar fuel synthesis by artificial photosynthesis; predicting the optical, electronic and redox properties of photocatalysts

“…The most well-known of these photocatalysts are the inorganic solids [1][2][3]6], mostly oxides but also sulfides and selenides, the former including titanium dioxide [13][14][15], the quintessential photocatalyst. Perhaps less well-known, a range of supramolecular systems [16,17] and even organic polymers [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] have also been reported to act as photocatalysts. In this mini-review we will discuss computational work on modelling such photocatalysts in terms of the relevant material properties and processes, as well as what we believe to be key aspects to consider when performing such calculations.…”

“…Many photocatalysts are comprised of more than one material or phase and the exciton can dissociate on the interface between two of these phases/materials. The formation of heterostructures can be intentional, as for example in the carbon nitride-carbon nanodots [34] and carbon nitride-polypyrrole [29] systems, or an unintentional side-effect of the material's prep aration, as in for example the often used Degussa P25 titanium dioxide, which is a mixture of the anatase and rutile phases. Presence of these heterostructures can have a very significant effect on the photocatalytic activity.…”

Carbon-Based Metal-Free Electrocatalysis for Energy Conversion, Energy Storage, and Environmental Protection

“…Recently, metal-free photocatalysts based on carbon dots/g-C 3 N 4 have been reported [191]. Lee and co-workers [191] found that a very small loading of carbon dots (0.0016 wt%) embedded in the matrix of g-C 3 N 4 can lead to stable overall water splitting to H 2 and O 2 in a stoichiometric ratio under visible light for at least 200 days.…”

“…Lee and co-workers [191] found that a very small loading of carbon dots (0.0016 wt%) embedded in the matrix of g-C 3 N 4 can lead to stable overall water splitting to H 2 and O 2 in a stoichiometric ratio under visible light for at least 200 days. Remarkably, a solarto-hydrogen yield of 2% was obtained with a carbon dot loading of 0.48 wt% under AM 1.5G solar simulation [191].…”