Rational Design of Metallic NiTe_x (x = 1 or 2) as Bifunctional Electrocatalysts for Efficient Urea Conversion

Abstract

Electrocatalytic urea conversion (CO­(NH2)2 + H2O → N2 + 3H2 + CO2) is a facile and scalable technique for urea-rich wastewater treatment, meanwhile with hydrogen evolution reaction (HER). However, it remains great challenge to develop a bifunctional catalyst for both HER and urea oxidation reaction (UOR) simultaneously due to the torpid kinetics of 6 e– transfer during UOR. Here, graphene oxide (GO) induced phase-controlled synthesis of nickel tellurides derived from Ni foam (NF) as freestanding electrocatalysts is reported. Results show that NF-assisted NiTe composited with reduced graphene oxide (rGO) exhibits superior activity for both HER and UOR. With the combined merits of HER and UOR, an efficient electrolyzer with integrated NiTe/rGO/NF was constructed as anode and cathode, representing overall urea decomposition at a low overpotential and even being driven by a commercial cell of 1.5 V. The metallic character and phase dependence of NiTe2 and NiTe toward UOR were simulated by density functional theory (DFT). The collective effects of rGO incorporation in morphology and phase for exposing more active sites and effective electron transport were discussed. It is extended to the direction of human urine conversion as well. Our study provides new insights into robust bifunctional electrocatalysts for urea splitting, which indicates promise for sustainable hydrogen evaluation and wastewater remediation.

Synergistically Interfaced Bifunctional Transition Metal Selenides for High‐Rate Hydrogen Production Via Urea Electrolysis

“…UOR and urine electrolysis were conducted in human urine containing 1 M KOH (Figures S38 and 39). The UOR results revealed comparable activity with 1 M KOH containing urea, with slight increase in potential, due to the lower urea concentration in urine [48] . To illustrate the potential towards coupled waste treatment and hydrogen generation, urine electrolysis in urine with 1 M KOH was conducted (Figure 7 a and b).…”

Nickel Selenide Quantum Dot Applications in Electrocatalysis and Sensors

“…Urea is regarded as a potential energy source because it possesses the following: high energy density, high hydrogen content, abundant reserves, highly stable, easily stored and transported [108, 109]. Interestingly, urea is considered as an advanced hydrogen carrier because it utilizes a lower cell potential (0.37 V) than the water‐splitting reaction (1.23 V) [108, 110]. The electrooxidation reaction of urea is shown in Equation 5 and 6 [111]: …”

Solvent-Free Mechanochemical Synthesis and Characterization of Nickel Tellurides with Various Stoichiometries: NiTe, NiTe2 and Ni2Te3

“…Nickel tellurides have been tested as electrode material for the determination of uric acid and adenine in physiological fluids [ 7 ], glucose sensors [ 8 ], anode material for Li-ion batteries [ 9 ], supercapacitor [ 10 , 11 , 12 ], and solar cell [ 13 ] materials. The most attractive research area seems to be the possible use of nickel tellurides as electrocatalysts for hydrogen/oxygen evolution [ 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. The lower electronegativity of Te, when compared to S and Se, provides tellurides with a more metallic character, giving them ferromagnetic behavior and properties, which outperform sulfides and selenides when applied as electrocatalysts [ 21 ].…”

“…More recently, NiTe and NiTe 2 thin films have been prepared by electrodeposition [ 26 ] and chemical vapor deposition [ 27 ]. The hydro/solvothermal method is also widely used for preparation of nickel tellurides with different stoichiometries like NiTe [ 4 , 9 , 10 , 11 , 12 , 19 , 28 , 29 ], NiTe 2 [ 1 , 20 , 30 , 31 ], NiTe/NiTe 2 mixed phases [ 15 ], Ni 3 Te 2 [ 8 ] as well as a whole series of NiTe x nanorods with 1 ≤ x ≤ 2 [ 6 ].…”