Homogeneous Molecular Iron Catalysts for Direct Photocatalytic Conversion of Formic Acid to Syngas (CO+H₂)

Abstract

The catalytic decomposition of formic acid to generate syngas (a mixture of H2 and CO) is a highly valuable strategy for energy conversion. Syngas can be used directly in internal combustion engines or can be converted to liquid fuels, meeting future energy challenges in a sustainable manner. Herein, we report the use of homogeneous molecular iron catalysts combined with a CdS nanorods (NRs) semiconductor to construct a highly efficient photocatalytic system for direct conversion of formic acid to syngas at room temperature and atmospheric pressure. Under optimal conditions, the photocatalytic system presents an activity of 150 mmol gcatalyst−1 h−1 towards H2, and an apparent quantum yield (AQY) of 16.8 %, making it among the most active noble‐metal‐free photocatalytic systems for H2 evolution from formic acid under visible light. Meanwhile, these iron‐based molecular catalysts also demonstrate remarkable enhancement in CO evolution with robust stability. The mechanistic role of the molecular catalyst is further investigated by using cyclic voltammetry, which suggests the formation of FeI species as the key step in the catalytic conversion of formic acid to syngas.

Immobilization of Iron Minerals on a Layered Silicate for Enhancing its Solar Photocatalytic Activity toward H2 Production

“…− and H + , 3) the Fe(III) complex rapidly accepts the photogenerated electron from the excited CdS to produce Fe(II) species, 4) transfer of another electron from CO 2 − to Fe(II) species produces Fe(I) species which effectively reduce H + to yield H 2 (Irfan et al, 2020). In the present case, the immobilized FHS can act as a semiconductor photocatalyst enabling to both oxidize formate to produce H + and reduce H + to yield H 2 .…”

Improvement of microporous silicoaluminophosphate properties by Fe and Ti insertion for photocatalytic hydrogen generation under visible light

“…Furthermore, the presence of Fe in the SAPO4-5 or TAPSO4-5 framework improves the redox properties of the catalysts and can shift their absorption spectra to the visible range, offering then an optimum band gap energy [29]. Moreover, it has been shown that the presence of Fe in photo-catalysts, significantly boosts their activity by suppressing the rapid recombination of photo-generated charge carriers [32].…”

Interfacial band bending induced charge-transfer regulation over Ag@ZIF-8@g-C3N4 to boost photocatalytic CO2 reduction into syngas

“…9,10 More importantly, the syngas product is a key intermediate than can be converted to bulk chemicals via Fischer-Tropsch processes. 11,12 Although 2nd-and 3rd-row transition-metal-based complexes (such as Re, Ir, and Ru) are considered to be the most capable catalysts for photocatalytic CO 2 reduction, their high cost and scarcity hinder their industrial-scale application. 13,14 In the past few decades, various photocatalysts, such as TiO 2 , g-C 3 N 4 , layered double hydroxides (LDHs), and CdS, have been investigated in detail for the photocatalytic reduction of CO 2 .…”