PdSn/NiO/NaTaO3:La for photocatalytic ammonia synthesis by reduction of NO3− with formic acid in aqueous solution

Sirivithayapakorn

International Journal of Photoenergy

et al. 2020

Ammonium ( NH 4 + ) is an undesirable by-product of photocatalytic nitrate ( NO 3 − ) reduction since it is harmful to aquatic life once it converts into ammonia (NH3). This research investigated the removal efficiency of NO 3 − and for the first time quantified the relationships of initial nitrate concentrations ([ NO 3 − ]0) and photocatalyst dosages on the remaining ammonium ( NH 4 + ) in synthetic wastewater using photocatalytic reduction process with either nanoparticle titanium dioxide (TiO2) or 1.0%Ag-TiO2 under Ultraviolet A (UVA). The experiments were systematically carried out under various combinations of [ NO 3 − ]0 (10, 25, 50, 80, and 100 mg-N/L) and photocatalyst dosages (0.1, 0.5, 1.0, and 2.0 g). The NO 3 − removal efficiency of both photocatalysts was 98.96-99.98%, and the catalytic selectivity products were nitrogen gas (N2), nitrite ( NO 2 − ), and NH 4 + . Of the two photocatalysts under comparable experimental conditions, 1.0%Ag-TiO2 provided better NO 3 − removal efficiency. For both photocatalysts, the remaining NH 4 + was predominantly determined by [ NO 3 − ]0; higher [ NO 3 − ]0 led to higher NH 4 + . Multiple linear regression analysis confirmed the dominant role of [ NO 3 − ]0 in the remaining NH 4 + . The photocatalyst dosage could play an essential role in limiting NH 4 + in the treated wastewater, with large variation in [ NO 3 − ]0 from different sources.

Section: Introductionmentioning

confidence: 99%

Effects of Initial Nitrate Concentrations and Photocatalyst Dosages on Ammonium Ion in Synthetic Wastewater Treated by Photocatalytic Reduction

Sirivithayapakorn

International Journal of Photoenergy

et al. 2020

“…71 Currently, La-doped NaTaO3 photocatalysts has been successfully employed for the decomposition of refractory organic compounds, 72,73 reduction of CO2, 74 photocatalytic steam reforming of methane 74 and ammonia synthesis. 75 Regarding the synthetic prospective of NaTaO3 photocatalysts, direct band gap NaTaO3 (4.1 eV) with orthorhombic structure are obtained from the traditional solid state route displaying low activity for water splitting. Replacing the typical solid state by sol-gel technique, NaTaO3 with a monoclinic structure possessing an indirect band gap (3.9 eV) with high density of states near the band edges are produced, evincing a higher activity compared to solid state synthesized NaTaO3.…”

Section: Ternary Oxide Photocatalystsmentioning

confidence: 99%

Nanostructured materials for photocatalysis

et al. 2019

“…For the produced NO 3 – , some recent pioneering studies have confirmed the feasibility of its photocatalytic conversion to NH 3 . Following the probable routes ( and ), the photoinduced holes are consumed with the electron donors (e.g., HCOOH), resulting in a high selectivity in NH 3 production (up to ∼97%). , Considering these promising routes, it is highly anticipated to offer an alternative strategy for the efficient photocatalytic NH 3 production. …”

Section: Principles and Challenges In Nitrogen Reduction Reaction (Nrr)mentioning

confidence: 99%

Rational Catalyst Design for N₂ Reduction under Ambient Conditions: Strategies toward Enhanced Conversion Efficiency

et al. 2020

Ammonia (NH 3 ), one of the basic chemicals in most fertilizers and a promising carbon-free energy storage carrier, is typically synthesized via the Haber−Bosch process with high energy consumption and massive emission of greenhouse gases. The photo/ electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions has attracted increasing interests recently, providing alternative routes to realize green NH 3 synthesis. Despite rapid advances achieved in this most attractive research field, the unsatisfactory conversion efficiency including a low NH 3 yield rate, and limited Faradaic efficiency or apparent quantum efficiency still remains as a great challenge. The NRR performance is intrinsically related to the electronic and surface structure of catalysts. Rational design and preparation of advanced catalysts are indispensable to improve the performance (e.g., activity and selectivity) of NRR. In this Review, various strategies for the development of desirable catalysts are comprehensively summarized, mainly containing the defect engineering, structural manipulation, crystallographic tailoring, and interface regulation. State-of-the-art heterogeneous NRR catalysts, prevailing theories and underlying catalytic mechanisms, together with current issues, critical challenges, and perspectives are discussed. It is highly expected that this Review will promote the understanding of recent advances in this area and stimulate greater interests for designing promising NRR catalysts in future.