Hydrogen Production from Formic Acid by In Situ Generated Ni/CdS Photocatalytic System under Visible Light Irradiation

Abstract

Simple and practical noble‐metal‐free catalyzed hydrogen production from sustainable resources, such as renewable formic acid, is highly desirable. Herein, the development of an efficient photocatalytic hydrogen production from aqueous solution of formic acid using in situ generated Ni/CdS photocatalytic system was described. CdS−Cys (Cys=l‐cysteine) quantum dots (QDs) acting as photocatalyst with Ni(OAc)2 as H2 production catalyst precursor, a 94 % yield was obtained within 5 h under visible light irradiation at 50 °C. The average rate of H2 production reached up to 282 μmol mg−1 h−1 with 99.8 % H2 selectivity. Mechanistic studies indicate cooperation of dynamic quenching and static quenching of CdS−Cys QDs by Ni(OAc)2. Especially, Ni0, generated in the dynamic quenching, accelerated the electron transfer by acting as an electron outlet and enhancing the stability of CdS to slow down the photocorrosion distinctly, delivering efficient H2 production with high selectivity. Our study will inspire exploration of various efficient non‐noble‐metal catalysts for practical H2 production from bio‐based formic acid.

The synergy of in situ-generated Ni0 and Ni2P to enhance CO adsorption and protonation for selective CH4 production from photocatalytic CO2 reduction

“…Ni 3 (PO 4 ) 2 ) under light irradiation. The presence of Ni 0 sites is believed to increase the CH 4 yield as Ni 0 plays an active role in the methanation of CO. 59,60 Consequently, the Ni 0 -Ni 2 P/CN photocatalytic system is in situ generated by light irradiation. The coexisting active sites of Ni 2 P and Ni 0 synergistically work to enhance the production of CH 4 .…”

Efficient H2 Production from Biomass-Based HCO2H by Cooperation of Quantum Dots Photocatalysts with Weak HCHO Adsorption and In Situ Generated Ni0

“…Very recently, we developed H 2 production from HCO 2 H aqueous solution by using a Ni/CdS-Cys photocatalytic system generated in situ, with CdS-Cys QDs as a photocatalyst and Ni­(OAc) 2 as a cocatalyst precursor, in 94% yield within 5 h under visible-light irradiation at 50 °C, with an average rate of 282 mol mg –1 h –1 and a 99.8% H 2 selectivity . However, this catalytic system was incompatible with the small amount of simultaneously generated HCHO in the biomass-based HCO 2 H, produced by efficient direct hydrolysis–oxidation of raw biomass such as wheat straw, etc., contributed by DMSO promotion. , Although elegant progresses have been made for oxidation of biomass to HCO 2 H by photocatalytic oxidation, , a small amount of HCHO was still contained, and the DMSO-promoted direct hydrolysis–oxidation of biomass to HCO 2 H still keeps the priority of high efficiency, especially for the raw biomass.…”

“…Initially, CdS/ZnS-S 2– QDs with a mol ratio of 1:6:0.25 of precursors Cd, S, and Zn were tried. The concentration of commercial HCO 2 H was adjusted to the lab-made biomass-based HCO 2 H concentration (1.0 M) for the initial investigation. ,, As the observed promoted H 2 production by formate (20 mol %) in the catalytic system of Ni/CdS-Cys, a model experiment consisting of HCO 2 H (2.0 mmol), CdS/ZnS-S 2– QDs (1.0 mg), Ni­(OAc) 2 ·4H 2 O (0.25 mol %), and HCO 2 Na (20 mol %) in aqueous solution was investigated. H 2 was obtained in 64% yield with a 99.7% selectivity at 50 °C for 5 h in an Ar atmosphere under 10 W blue LED irradiation (Table , entry 1).…”

“…2,7,8 However, efficient H 2 production from biomass-based HCO 2 H is still limited in noble-metal catalysis, such as using [Ir], [Pd], [Pt], and [Ru] catalysts. 6c−f The major reason for intolerance of biomass-based HCO 2 H to the efficient and simple noble-metal-free catalytic system of H 2 production from commercial HCO 2 H, such as using CdS-Cys (Cys = L-cysteine) quantum dots (QDs) as the photocatalyst with Ni(OAc) 2 as the H 2 production catalyst precursor, 9 is containing a small amount of inseparable HCHO by simple distillation in the resulting HCO 2 H media.…”

“…Therefore, efficient H 2 production from biomass has long been pursued . During these endeavors, performing H 2 production via a formic acid (HCO 2 H) intermediate from biomass both facilitates efficient H 2 production − and can avoid the issues of H 2 storage, as HCO 2 H is regarded as a promising hydrogen storage carrier. ,, However, efficient H 2 production from biomass-based HCO 2 H is still limited in noble-metal catalysis, such as using [Ir], [Pd], [Pt], and [Ru] catalysts. − The major reason for intolerance of biomass-based HCO 2 H to the efficient and simple noble-metal-free catalytic system of H 2 production from commercial HCO 2 H, such as using CdS-Cys (Cys = l -cysteine) quantum dots (QDs) as the photocatalyst with Ni­(OAc) 2 as the H 2 production catalyst precursor, is containing a small amount of inseparable HCHO by simple distillation in the resulting HCO 2 H media.…”