Potassium‐Ion‐Assisted Regeneration of Active Cyano Groups in Carbon Nitride Nanoribbons: Visible‐Light‐Driven Photocatalytic Nitrogen Reduction

Abstract

As am etal-free nitrogen reduction reaction (NRR) photocatalyst, g-C 3 N 4 is available from as calable synthesis at low cost. Importantly,i tc an be readily functionalizedt o enhance photocatalytic activities.H owever,t he use of g-C 3 N 4based photocatalysts for the NRR has been questioned because of the elusive mechanism and the involvement of Nd efects. This work reports the synthesis of ag -C 3 N 4 photocatalyst modified with cyano groups and intercalated K + (mCNN), possessing extended visible-light harvesting capacity and superior photocatalytic NRR activity (NH 3 yield: 3.42 mmol g À1 h À1 ). Experimental and theoretical studies suggest that the -C Ni nm CNN can be regenerated through ap athway analogous to Mars van Krevelen process with the aid of the intercalated K + .T he results confirm that the regeneration of the cyano group not only enhances photocatalytic activity and sustains the catalytic cycle,b ut also stabilizes the photocatalyst.

Progress and challenges in photocatalytic ammonia synthesis

“…Recently, a g-C3N4 catalyst modified with cyano groups (-C ≡ N) and incorporated K + Please do not adjust margins (mCNN) was prepared as an efficient photocatalyst for NRR. 55 In relative to pristine g-C3N4, the absorption spectrum of mCNN was extended to the whole visible region (Fig. 5a), resulting from the π-π* electronic transitions in the conjugated heterocyclic rings and n-π* electronic transitions at the active N defect sites (-C≡N), which indicated that the introduction of the N-defect of -C ≡ N could significantly change the optical properties.…”

“…The surface regulations, including defect engineering and morphology engineering, significantly determine the photocatalytic activity because they can promote the surface adsorption and activation of N2. 23,[31][32][33][34][35][36][37][38][39][40][54][55][56][57][64][65][66][67][68][69][70][71] The interface modulations, including the modification with cocatalysts and semiconductors, greatly affect the charge transfer and separation efficiency. [89][90][91][92][93][94][95][96][97][98][99][100][101][109][110][111] We will discuss these factors one by one below.…”

A nine-fold enhancement of visible-light photocatalytic hydrogen production of g-C3N4 with TCNQ by forming a conjugated structure

“…32 Moreover, the C 1s XPS peaks of 5% TCNQ-C 3 N 4 are tted to three positions at 284.8 eV, 286.1 eV and 288.5 eV, with the 286.1 eV peak being associated with -C^N. 33 The binding energy shis in the binary hybrids are ascribed to an intense interaction between the two components. 34 Besides, the peak area of the 286.1 eV peak exhibited a decrease which may be attributed to the sp 3 hybridization transforming to sp 2 hybridization.…”

Defect Engineering of Photocatalysts for Solar Energy Conversion

“…As numerous achievements have been obtained upon the modulation of light absorption, charge separation, and PC reactions by defects engineering, it is necessary to evaluate the atomic structures of the defects and determine the relationship between the structure and catalytic activities by characterization techniques. [101][102][103][104][105][106][107][108][109][110][111][112][113][114][115]…”

“…www.advancedsciencenews.com www.solar-rrl.com spectra of C K-edge and N K-edge for g-C 3 N 4 and defective g-C 3 N 4 (Figure 12e,f ), indicating the presence of nitrogen defects. [108] Meanwhile, EELS can be used to analyze the distribution of the defects in the photocatalysts. As shown from Ti-L edge spectra, the enhanced concentration of Ti 3þ ions indicated the increasing content of OVs in reduced TiO 2 crystals.…”