Mamutjan Tursun

Bio: Mamutjan Tursun is an academic researcher from Xi'an Jiaotong University. The author has contributed to research in topics: Transition metal & Vacancy defect. The author has co-authored 2 publications.

Vacancy-triggered and dopant-assisted NO electrocatalytic reduction over MoS2.

Abstract: Nitric oxide electroreduction reaction (NOER) is an efficient method for NH3 synthesis and NOx-related pollutant treatment. However, current research on NOER catalysts mainly focuses on noble metals and single atom catalysts, while low-cost transition metal dichalcogenides (TMDCs) are rarely considered. Herein, by applying density functional theory (DFT) calculations, we study the catalytic performance of NOER over 2H-MoS2 monolayers with the most common S vacancies and some Mo atoms substituted by transition metal atoms (denoted as TM-MoS2@VS). Our results show that an S vacancy and a heteroatom substitution tend to form a first nearest neighbour (1NN) pair, which greatly improves the NOER catalytic performance of 2H-MoS2. The S vacancy site can trigger NOER by strongly adsorbing a NO molecule and elongating the NO bond, while the heteroatom dopant can assist NOER by tuning the electron donating capability of 2H-MoS2 which breaks the linear scaling relations among key reaction intermediates. At low NO coverage, NH3 can be correspondingly yielded at -0.06 and -0.38 V onset potentials over the Pt- and Au-doped MoS2 catalysts with S vacancies (Pt-MoS2@VS and Au-MoS2@VS). At high NO coverage, N2O/N2 is thermodynamically favored. Meanwhile, the competing hydrogen evolution reaction (HER) is suppressed. Thus, the Pt-MoS2@VS catalysts are promising candidates for NOER. In addition, coupling the substitutional doping of Mo atoms to S vacancies presents great potential in improving the catalytic activity and selectivity of MoS2 for other reactions. In general, the strategy of coupling hetero-metal doping and chalcogen vacancy can be extended to enhance the catalytic activity of other TMDCs.

Recent advances in nanostructured heterogeneous catalysts for N-cycle electrocatalysis

Abstract: To restore the natural nitrogen cycle (N-cycle), artificial N-cycle electrocatalysis with flexibility, sustainability, and compatibility can convert intermittent renewable energy (e.g., wind) to harmful or value-added chemicals with minimal carbon emissions. The background of such N-cycles, such as nitrogen fixation, ammonia oxidation, and nitrate reduction, is briefly introduced here. The discussion of emerging nanostructures in various conversion reactions is focused on the architecture/compositional design, electrochemical performances, reaction mechanisms, and instructive tests. Energy device advancements for achieving more functions as well as in situ/operando characterizations toward understanding key steps are also highlighted. Furthermore, some recently proposed reactions as well as less discussed C–N coupling reactions are also summarized. We classify inorganic nitrogen sources that convert to each other under an applied voltage into three types, namely, abundant nitrogen, toxic nitrate (nitrite), and nitrogen oxides, and useful compounds such as ammonia, hydrazine, and hydroxylamine, with the goal of providing more critical insights into strategies to facilitate the development of our circular nitrogen economy.

High-Throughput Screening of Efficient Biatom Catalysts Based on Monolayer Carbon Nitride for the Nitric Oxide Reduction Reaction.

Abstract: Exploring efficient catalysts for the nitric oxide reduction reaction (NORR) toward NH3 synthesis is becoming increasingly important for tackling both NH3 synthesis and NO removal problems. Currently, only a few NORR catalysts have been proposed, which are exclusively concentrated on bulk metals or single-atom catalysts. Here, taking monolayer C2N as an example, we explore the potential of biatom catalysts (BACs) for direct NO-to-NH3 conversion by means of high-throughput first-principles calculations. According to a rational five-step screening strategy, a promising BAC of Cr2-C2N is successfully screened out, exhibiting high stability, activity, and selectivity and a low kinetic barrier for the NORR toward NH3 synthesis. Importantly, the adsorption energy of N atoms (ΔE*N) and the Gibbs free energy of NO adsorption (ΔG*NO) are identified as effective descriptors for efficient NORR catalysts. In addition, through tuning the NO coverage, the NORR on Cr2-C2N could produce different products of NH3 and N2O, providing the possibility to realize controllable multiproduct BACs. These findings not only suggest the great potential of BACs for direct NO-to-NH3 conversion but also help in rationally designing high-performance BACs.

Enhancing Electrocatalytic NO Reduction to NH3 by the CoS Nanosheet with Sulfur Vacancies.

Abstract: Electrochemical reduction of NO to NH3 is of great significance for mitigating the accumulation of nitrogen oxides and producing valuable NH3. Here, we demonstrate that the CoS nanosheet with sulfur vacancies (CoS1-x) behaves as an efficient catalyst toward electrochemical NO-to-NH3 conversion. In 0.2 M Na2SO4 electrolyte, such CoS1-x displays a large NH3 yield rate (44.67 μmol cm-2 h-1) and a high Faradaic efficiency (53.62%) at -0.4 V versus the reversible hydrogen electrode, outperforming the CoS counterpart (27.02 μmol cm-2 h-1; 36.68%). Moreover, the Zn-NO battery with CoS1-x shows excellent performance with a power density of 2.06 mW cm-2 and a large NH3 yield rate of 1492.41 μg h-1 mgcat.-1. Density functional theory was performed to obtain mechanistic insights into the NO reduction over CoS1-x.

Nitric oxide electrochemical reduction reaction on transition metal-doped MoSi2N4 monolayers.

Abstract: Nitric oxide electrochemical reduction (NOER) reactions are usually catalyzed by noble metals. However, the commercial applications are limited by the low atomic utilization and high price, which prompt researchers to turn their attentions to single-atom catalysts (SACs). Recently, a novel two-dimensional semiconducting material MoSi2N4 (MSN) has been synthesized and is suitable for the substrate of SACs due to its high stability, carrier mobility and mechanical strength. Herein, we employed first principles calculations to investigate the catalytic properties of transition metal doped MoSi2N4 monolayers (labelled as TM-MSN, where TM is a transition metal atom from 3d to 5d except Y, Tc, Cd, La-Lu and Hg) in NO reduction. The calculated results demonstrate that the introduction of Zr, Pd, Pt, Mn, Au, or Mo atoms can greatly improve the catalytic NOER performance of a pristine MSN monolayer. Zr-MSN and Pt-MSN monolayers at low coverage exhibit the most superior catalytic activity and selectivity for NH3 production with a limiting potential of 0 and -0.10 V. This work may help guide the application of MSN monolayer in the area of energy conversion.