Synergistically enhancing nitrate reduction into N2 in water by N-doped Pd–Cu biochar bimetallic single-atom electrocatalysis

Abstract

Noble metal materials have been identified as high efficiency catalysts for electrocatalytic reduction of nitrate, and the synthesis and manufacture of high catalytic activity and environmentally friendly catalysts of activating hydrogen for water purification applications is extremely attractive. In this work, the Pd–Cu single-atom catalysts (Pd–Cu-N-BC) were first prepared by direct growth of Pd–Cu single-atom on bamboo biochar by regulating the concentration of precursors and doping method, and then enhanced electrocatalytic reduction nitrate performance and N2 generation. The results showed that Pd–Cu-N-BC displayed excellent catalytic activity and reusability in electrocatalytic reduction nitrate with a low potential of 0.47 V vs. RHE (@10 mA cm−2). The maximum nitrate removal efficiency and N2 generation could reach about 100% and 72.32% within 180 min, respectively. The density functional theory (DFT) calculations confirmed that Cu atoms could catalyze the electrochemical reduction of nitrate to nitrite, and Pd atoms anchored in the nitrogen-doped biochar (N-BC) lattice could catalyze electrochemical reduction of nitrite to N2 involving the formation of hydrogen radical (H*). The characterization results of XANES showed that electronic synergistic effect between Pd and Cu single atoms significantly promotes the N2 production through hydrogenation while inhibiting the generation of byproducts, leading to significantly enhanced electrocatalytic reduction of nitrate to N2. Finally, Pd–Cu-N-BC was designed as a 3D particle electrode for enhanced electrocatalytic reduction of nitrate, exhibiting excellent stability and reusability, which could be considered as a suitable candidate for applications in the remediation of nitrate contamination. Graphical Abstract

Recent Progress and Perspectives on Transition Metal-Based Electrocatalysts for Efficient Nitrate Reduction

“…Au/Cu SAA had excellent ammonia selectivity with an FE of 99.69% at −0.80 V vs RHE and good stability after 20 consecutive cycles. In addition, a Pd-doped Cu SAC (Pd-Cu-N-BC) exhibiting excellent catalytic performance was prepared by Zhang et al 152 This catalyst could achieve 72.32% N 2 selectivity and 100% nitrate removal within 3 h and still have excellent stability after three working cycles. DFT calculations showed that this excellent catalytic performance was attributed to the electronic synergistic effect of two single-atoms, Cu and Pd.…”

“…This can destroy the oxygencarrying mechanism of red blood cells, which can lead to "blue baby syndrome" in infants. 11,15,16 In addition, excessive nitrates and nitrites can also lead to gastrointestinal cancers in adults.…”

“…Nitrite can then oxidize ferrous ions in hemoglobin to form trivalent iron. This can destroy the oxygen-carrying mechanism of red blood cells, which can lead to “blue baby syndrome” in infants. ,, In addition, excessive nitrates and nitrites can also lead to gastrointestinal cancers in adults. According to the U.S. Environmental Protection Agency and the World Health Organization, the concentrations of NO 3 – , NO 2 – , and NH 4 + in drinking water should not exceed 10, 0.03, and 0.4 mg-N L –1 , respectively .…”

In–Sb Covalent Bonds over Sb2Se3/In2Se3 Heterojunction for Enhanced Photoelectrochemical Water Splitting

“…Today, with the rapid development of the global economy, environmental pollution and energy shortages need to be urgently addressed. Hydrogen is a clean and efficient renewable energy source, and among numerous hydrogen production methods, photoelectrochemical (PEC) water splitting can efficiently produce hydrogen from abundant sunlight. − Since TiO 2 was initially reported as a photoelectrode for water splitting, numerous light-absorbing semiconductor materials, such as ZnO, g-C 3 N 4 , CdS, and BiVO 4 , have been employed in PEC water splitting. Nevertheless, almost none of them are well qualified for a satisfactory light response range, environmental and human friendliness, or high corrosion resistance simultaneously.…”