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We improve n-type lead chalcogenides by adding GaSb to reduce lattice thermal conductivity and achieve conduction band convergence. This significantly enhances the thermoelectric performance of n-type PbS, making it comparable to its p-type counterpart.

Recent success in exfoliating violet or Hittorf's phosphorus down to monolayer reignites the research passion in this ancient yet mysterious material, questing for superior electronic and optoelectronic functionalities. Unfortunately, the poor air stability that plagues black phosphorus also exists in the violet counterpart. Aiming to provide more insight into the degradation chemistry and accordingly find a facile solution for it, herein, we employ concerted elemental, chemical and vibrational spectroscopies to reveal the critical role of oxygen and water in the degradation mechanism and pathway of violet phosphorus in ambient condition. Thereafter, a simple passivation approach by oxide encapsulation is demonstrated to realize air-stable violet phosphorus photodetector device. As the proof-of-concept, the photodetector fabricated accordingly shows superior figures of merit with ultralow dark current (< 10−13 A), high low-light responsivity (6 A W−1) and fast response time (< 10 ms) in the ultraviolet to visible spectrum, as well as great chemical robustness against harsh environments.

Aqueous aluminum metal batteries (AMBs) are regarded as one of the most sustainable energy storage systems among post-lithium-ion candidates, which is attributable to their highest theoretical volumetric capacity, inherent safe operation, and low cost. Yet, the development of aqueous AMBs is plagued by the incapable aluminum plating in an aqueous solution and severe parasitic reactions, which results in the limited discharge voltage, thus making the development of aqueous AMBs unsuccessful so far. Here, we demonstrate that amorphization is an effective strategy to tackle these critical issues of a metallic Al anode by shifting the reduction potential for Al deposition. The amorphous aluminum (a-Al) interfacial layer is triggered by an in situ lithium-ion alloying/dealloying process on a metallic Al substrate with low strength. Unveiled by experimental and theoretical investigations, the amorphous structure greatly lowers the Al nucleation energy barrier, which forces the Al deposition competitive to the electron-stealing hydrogen evolution reaction (HER). Simultaneously, the inhibited HER mitigates the passivation, promoting interfacial ion transfer kinetics and enabling steady aluminum plating/stripping for 800 h in the symmetric cell. The resultant multiple full cells using Al@a-Al anodes deliver approximately a 0.6 V increase in the discharge voltage plateau compared to that of bare Al-based cells, which far outperform all reported aqueous AMBs. In both symmetric cells and full cells, the excellent electrochemical performances are achieved in a noncorrosive, low-cost, and fluorine-free Al2(SO4)3 electrolyte, which is ecofriendly and can be easily adapted for sustainable large-scale applications. This work brings an intriguing picture of the design of metallic anodes for reversible and high-voltage AMBs. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) C.Y. acknowledges funding supported by the National Natural Science Foundation of China (grant no. 52101246) and the Fundamental Research Funds for the Central Universities (grant no. 5710010721). Q.Y. acknowledges funding support from the Singapore MOE AcRF Tier 1 grant no. 2020-T1-001- 031 and the Singapore A*STAR project A19D9a0096. G.Y. acknowledges funding support from the Camille Dreyfus Teacher-Scholar Award and the Welch Foundation Award F1861.

Synthesizing urea from nitrate and carbon dioxide through an electrocatalysis approach under ambient conditions is extraordinarily sustainable. However, this approach still lacks electrocatalysts developed with high catalytic efficiencies, which is a key challenge. Here, we report the high-efficiency electrocatalytic synthesis of urea using indium oxyhydroxide with oxygen vacancy defects, which enables selective C-N coupling toward standout electrocatalytic urea synthesis activity. Analysis by operando synchrotron radiation-Fourier transform infrared spectroscopy showcases that *CO2NH2 protonation is the potential-determining step for the overall urea formation process. As such, defect engineering is employed to lower the energy barrier for the protonation of the *CO2NH2 intermediate to accelerate urea synthesis. Consequently, the defect-engineered catalyst delivers a high Faradaic efficiency of 51.0%. In conjunction with an in-depth study on the catalytic mechanism, this design strategy may facilitate the exploration of advanced catalysts for electrochemical urea synthesis and other sustainable applications. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) C.Y. acknowledges funding supported by the National Natural Science Foundation of China (Grant 52101246) and the Fundamental Research Funds for the Central Universities (Grant 5710010721). Q.Y. acknowledges funding support from Singapore MOE AcRF Tier 1 Grant 2020-T1-001-031 and Singapore A*STAR project A19D9a0096. G.Y. acknowledges funding support from the Camille Dreyfus TeacherScholar Award and Welch Foundation Award F-1861. The authors acknowledge computing resources from the National Supercomputing Centre, Singapore. This work is also supported by the Users with Excellence program of Hefei Science Center of CAS (2020HSC-UE003) and the Fundamental Research Funds for the Central Universities (WK2310000099).

With the excessive consumption of non-renewable resources, the exploration of effective and durable materials is highly sought after in the field of sustainable energy conversion and storage system. In this aspect, metal-organic frameworks (MOFs) are a new class of crystalline porous organic-inorganic hybrid materials. MOFs have recently been gaining traction in energy-related fields. Owing to the coordination flexibility and multiple accessible oxidation states of vanadium ions or clusters, Vanadium-MOFs (VMOFs) possess unique structural characteristics and satisfactory electrochemical properties. Furthermore, V-MOFs derived materials also exhibit superior electrical conductivity and stability when used as electrocatalysts and electrode materials. This review summarizes the research progress of V-MOFs (inclusive of pristine V-MOFs, V/M-MOFs and POV-based MOFs) and their derivatives (vanadium oxides, carboncoated vanadium oxide, vanadium phosphate, vanadate, and other vanadium doped nanomaterials) in electrochemical energy conversion (water splitting, oxygen reduction reaction) and energy storage (supercapacitor, rechargeable battery). Future possibilities and challenges for V-MOFs and their derivatives in terms of design and synthesis are discussed. Lastly, their applications in energy-related fields are also highlighted. Ministry of Education (MOE) National Research Foundation (NRF) Published version The authors gratefully acknowledge the National Natural Science Foundation of China (Nos. 51972067, 22001021, 51802044, 51902062 and 51802043), Guangdong Natural Science Funds for Distinguished Young Scholar (No.2019B151502039), Natural Science Foundation of Jiangsu Province (No. BK20201048), Natural Science Research Project of Higher Education Institutions in Jiangsu Province (No. 20KJB150008), Singapore MOE AcRF Tier 1(No. 2020‐T1‐001‐031), the Open Fund of State Key Laboratory of Tea Plant Biology and Utilization (No.SKLTOF20190119), and the National Research Foundation of Singapore (NRF) Investigatorship (No. NRF2016NRF‐NRFI001‐22).

Although Ga doping can weaken the electron phonon coupling of n-type PbTe, Ga-doped PbTe has a relatively low carrier concentration (n) and high lattice thermal conductivity (κlat), resulting in a lower figure of merit (ZT) compared with those of other top-performing n-type PbTe-based thermoelectric materials. Herein, we report the extraordinary role of Zn in enhancing the thermoelectric performance of Ga-doped PbTe. It is discovered that Zn can simultaneously improve the electronic transport properties and decrease the κlat of Ga-doped PbTe, thereby affording a record high ZTavg ~1.26 at 400–873 K, with a maximum ZT value of 1.55 at 723 K. The isoelectronic substitution of Zn for Pb in Ga-doped PbTe increases the electrical conductivity and n by inducing the nucleation and growth of Ga2Te3 in the second phase. The formation of Ga2Te3 results in nonstoichiometric and Te deficiency in the PbTe matrix, which increases the number of electron carriers. Additionally, discordant Zn and Ga atoms with the highest displacement of ~0.35 Å for Zn alloying, as well as Ga2Te3 nanocrystals ranging from 30 to 200 nm coherently embedded into the PbTe matrix effectively weaken the phonon modes and scatter heat-carrying phonons, resulting in a significant reduction in κlat. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) Submitted/Accepted version This study was supported primarily by the Department of Energy, Office of Science Basic Energy Sciences under grant DE-SC0014520, DOE Office of Science (sample preparation, synthesis, XRD, TE measurements, TEM measurements, DFT calculations), and Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China (2021ZZ127). The authors acknowledge the Minjiang Scholar Professorship (GXRC-21004) and the National Natural Science Foundation of China (61728401). The authors acknowledge the EPIC facility of Northwestern University’s NUANCE Center, which received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1720139) at the Materials Research Center, International Institute for Nanotechnology (IIN), Keck Foundation, State of Illinois, through the IIN; and the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-06CH11357 and DE-AC02-05CH11231. Access to facilities for high-performance computational resources at the Northwestern University is acknowledged. The authors acknowledge Singapore MOE AcRF Tier 2 under Grant No. 2018-T2-1- 010, Singapore A*STAR project A19D9a0096, and the support from FACTs of Nanyang Technological University for sample analysis.

K+ doping into the Na-site of a Na3V2(PO4)2O2F cathode creates Na vacancies and increases disordering in the crystal structure, which dramatically accelerates Na ion diffusivity with outstanding rate and cycle performances in sodium-ion full batteries.

Li+, Na+ co-stabilized vanadium oxide nanobelts with a bilayer structure are prepared via a quick one-pot eutectic oxidation process. Faster charge-transfer/ion-diffusion kinetics and robust architecture lead to a superior zinc-ion storage performance.

Doping high electrical conductivity Nb5Ge3 precipitates into GeTe results in nanoprecipitates phonon scattering, while retaining electrical mobility. As a result, thermoelectric zT of GeTe is drastically enhanced to 2.0 at 723 K.

Electronic waste (e-waste) recycling is one of the central frameworks of the circular economy.

The magnetometer is a multi-parameter system, parameters optimization is always the problem to improve the sensitivity of the atomic magnetometer. Multiple parameters hardly decide the optimized conditions in the experiments because of the influence of several parameters and parameters may interact with each other. Besides, the influence of parameters on the signal-to-noise ratio can hardly be analyzed theoretically due to the complex physical configuration. We used a generalized polynomial chaos expansion to construct an agent model for the SERF atomic magnetometer to replace its complex physical model, and used a variance-based sobol method to perform a global sensitivity analysis of the parameters in this paper. The mathematical method of uncertainty quantification is used to comprehensively analyze six parameters’ effect on SERF atomic magnetometer performance. The results show that the probe laser power has the greatest impact on the atomic magnetometer, and it is the parameter with the highest degree of linearity with the atomic magnetometer. In accordance with the results of the uncertainty quantification analysis, the parameters of the probe laser power of the SERF atomic magnetometer were experimentally optimized, and the performance of the magnetometer was significantly improved.

With ever-increasing energy consumption and continuous rise in atmospheric CO2 concentration, electrochemical reduction of CO2 into chemicals/fuels is becoming a promising yet challenging solution. Sn-based materials are identified as attractive electrocatalysts for the CO2 reduction reaction (CO2 RR) to formate but suffer from insufficient selectivity and activity, especially at large cathodic current densities. Herein, we demonstrate that Cu-doped SnS2 nanoflowers can undergo in situ dynamic restructuring to generate catalytically active S-doped Cu/Sn alloy for highly selective electrochemical CO2 RR to formate over a wide potential window. Theoretical thermodynamic analysis of reaction energetics indicates that the optimal electronic structure of the Sn active site can be regulated by both S-doping and Cu-alloying to favor formate formation, while the CO and H2 pathways will be suppressed. Our findings provide a rational strategy for electronic modulation of metal active site(s) for the design of active and selective electrocatalysts towards CO2 RR. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) We acknowledge the funding support from Singapore Ministry of Education AcRF Tier 1: RG5/20 and RG4/20; Tier 2: MOET2EP10120-0002, and Agency for Science, Technology and Research (A*Star) AME IRG: A20E5c0080.Great thanks are given to the Facility for Analysis, Characterization, Testing and Simulation (FACTS) of Nanyang Technological University, Singapore. We also like to acknowledge 111 project (D18023 ) from Zhengzhou University for their support of this work.

Metal-free 2D phosphorus-based materials are emerging catalysts for ammonia (NH3 ) production through a sustainable electrochemical nitrogen reduction reaction route under ambient conditions. However, their efficiency and stability remain challenging due to the surface oxidization. Herein, a stable phosphorus-based electrocatalyst, silicon phosphide (SiP), is explored. Density functional theory calculations certify that the N2 activation can be realized on the zigzag Si sites with a dimeric end-on coordinated mode. Such sites also allow the subsequent protonation process via the alternating associative mechanism. As the proof-of-concept demonstration, both the crystalline and amorphous SiP nanosheets (denoted as C-SiP NSs and A-SiP NSs, respectively) are obtained through ultrasonic exfoliation processes, but only the crystalline one enables effective and stable electrocatalytic nitrogen reduction reaction, in terms of an NH3 yield rate of 16.12 µg h-1 mgcat. -1 and a Faradaic efficiency of 22.48% at -0.3 V versus reversible hydrogen electrode. The resistance to oxidization plays the decisive role in guaranteeing the NH3 electrosynthesis activity for C-SiP NSs. This surface stability endows C-SiP NSs with the capability to serve as appealing electrocatalysts for nitrogen reduction reactions and other promising applications. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) Submitted/Accepted version Q.Y. acknowledges the funding support from Singapore MOE AcRF Tier 1 under grant no. 2020-T1-001-031 and Singapore A*STAR project A19D9a0096. C.X. thanks the support from the Ministry of Education Singapore under AcRF-Tier1 (2021-T1-002-012, RG65/21.

Thermoelectric materials can be potentially employed in solid-state devices that harvest waste heat and convert it to electrical power, thereby improving the efficiency of fuel utilisation. The spectacular increases in the efficiencies of these materials achieved over the past decade have raised expectations regarding the use of thermoelectric generators (TEG) in various energy saving and energy management applications, especially at mid-high temperature (400-900 oC). However, several important issues that prevent successful TEG commercialisation remain unresolved in good part because of lack of a research roadmap. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) Submitted/Accepted version TE materials research at NTU is supported by Singapore MOE AcRF Tier 2 under grant nos. 2018-T2-1-010, Singapore A*STAR Pharos Program SERC 1527200022 and Singapore A*STAR project A19D9a0096. Basic TE materials research at Northwestern University is supported by the US Department of Energy, Office of Science and Office of Basic Energy Sciences, under award no. DE-SC0014520.

The reaction of MnTe with AgSbTe2 in an equimolar ratio (ATMS) provides a new semiconductor, AgMnSbTe3. AgMnSbTe3 crystallizes in an average rock-salt NaCl structure with Ag, Mn, and Sb cations statistically occupying the Na sites. AgMnSbTe3 is a p-type semiconductor with a narrow optical band gap of ∼0.36 eV. A pair distribution function analysis indicates that local distortions are associated with the location of the Ag atoms in the lattice. Density functional theory calculations suggest a specific electronic band structure with multi-peak valence band maxima prone to energy convergence. In addition, Ag2Te nanograins precipitate at grain boundaries of AgMnSbTe3. The energy offset of the valence band edge between AgMnSbTe3 and Ag2Te is ∼0.05 eV, which implies that Ag2Te precipitates exhibit a negligible effect on the hole transmission. As a result, ATMS exhibits a high power factor of ∼12.2 μW cm-1 K-2 at 823 K, ultralow lattice thermal conductivity of ∼0.34 W m-1 K-1 (823 K), high peak ZT of ∼1.46 at 823 K, and high average ZT of ∼0.87 in the temperature range of 400-823 K.

A Bi–Ni bimetal nanosheet with mesoporous structure is prepared via a self-template electrochemical in situ method. The alloying effect between Bi and Ni regulated the electronic structure, thus improving the intrinsic activity of Bi–Ni catalyst.

Artificial nitrogen conversion reactions, such as the production of ammonia via dinitrogen or nitrate reduction and the synthesis of organonitrogen compounds via C-N coupling, play a pivotal role in the modern life. As alternatives to the traditional industrial processes that are energy- and carbon-emission-intensive, electrocatalytic nitrogen conversion reactions under mild conditions have attracted significant research interests. However, the electrosynthesis process still suffers from low product yield and Faradaic efficiency, which highlight the importance of developing efficient catalysts. In contrast to the transition-metal-based catalysts that have been widely studied, the p-block-element-based catalysts have recently shown promising performance because of their intriguing physiochemical properties and intrinsically poor hydrogen adsorption ability. In this Perspective, we summarize the latest breakthroughs in the development of p-block-element-based electrocatalysts toward nitrogen conversion applications, including ammonia electrosynthesis from N

Recently, rechargeable metal-ion batteries have been the research focus for their long cycle life and high energy density. In this special issue, we collected 30 researcch and review papers that cover the research progress of electrode materials, separators, and electrolytes in various advanced metal-ion and other energy storage devices.

Metal selenides are considered as a group of promising candidates as the anode material for sodium-ion batteries due to their high theoretical capacity. However, the intrinsically low electrical and ionic conductivities as well as huge volume change during the charge-discharge process give rise to an inferior sodium storage capability, which severely hinders their practical application. Herein, we fabricated In2Se3/CoSe2 hollow nanorods composed of In2Se3/CoIn2/CoSe2 by growing cobalt-based zeolitic imidazolate framework ZIF-67 on the surface of indium-based metal-organic framework MIL-68, followed by in situ gaseous selenization. Because of the CoIn2 alloy phase in between In2Se3 and CoSe2, a heterostructure consisting of two alloy/selenide interfaces has been successfully constructed, offering synergistically enhanced electrical conductivity, Na diffusion process, and structural stability, in comparison to the single CoIn2-free interface with only two metal selenides. As expected, this nanoconstruction delivers a high reversible capacity of 297.5 and 205.5 mAh g-1 at 5 and 10 A g-1 after 2000 cycles, respectively, and a superior rate performance of 371.6 mAh g-1 at even 20 A g-1.

Rose-petal-like superhydrophobic surfaces with strong water adhesion are promising for microdroplet manipulation and lossless droplet transfer. Assembly of self-grown micropillars on shape-memory polymer sheets with their surface adhesion finely tunable was enabled using a picosecond laser microprocessing system in a simple, fast, and large-scale manner. The processing speed of the wettability-finely-tunable superhydrophobic surfaces is up to 0.5 cm

Electrochemical reduction of CO2 into value-added chemicals has been envisioned as a promising strategy to alleviate the issue of increasing CO2 emissions. However, the sluggish oxygen evolution reaction (OER), as the anodic reaction, typically consumes approximately 90% of the electricity input, necessitating the development of an efficient OER for energy-saving purposes. Herein, we developed a unique heterostructure of multi-double (bi)-shelled Co-based spheres via a facile template-free method, in which each bi-shelled structure is composed of Co9Se8/Co9S8/CoO (Co-S-Se) with a symmetric configuration. These heterogeneous nanospheres possess both sufficient heterointerfaces and a high density of active sites and exhibit excellent OER activity in alkaline media with a low overpotential of 226 mV at 10 mA cm−2, a small Tafel slope of 46.5 mV dec−1, and long-term durability over 15 h. As a proof and concept, when coupled with a cathodic CO2 reduction reaction, the electrochemical performance of Pd nanosheets (NSs) for CO2 reduction can be significantly enhanced in terms of product selectivity and energy input. Our study might provide insight into the development of efficient OER electrocatalysts for practical CO2 reduction reactions.

To move away from fossil fuels, the electrochemical reaction plays a critical role in renewable energy sources and devices. The anodic oxygen evolution reaction (OER) is always coupled with these reactions in devices but suffers from large energy barriers. Thus, it is important for developing efficient OER catalysts with low overpotential. On the other hand, there are large amounts of metals in electronic waste (E-waste), especially various transition metals that are promising alternatives for catalyzing OER. Hence, this work, which focuses on upcycling Class II BaTiO3 Multilayer Ceramic Capacitors, of which two trillion were produced in 2011 alone. We achieved this by first using a green solvent extraction method that combined the ionic liquid Aliquat® 336 and hydrochloride acid to recover a mixed solution of Ni, Fe and Cu cations, and then using such a solution to synthesize high potential catalysts NiFe hydroxide and NiCu hydroxide for OER. NiFe-hydroxide has been demonstrated to have faster OER kinetics than the NiCu-hydroxide and commercial c-RuO2. In addition, it showed promising results after the chronopotentiometry tests that outperform c-RuO2. National Environmental Agency (NEA) National Research Foundation (NRF) Published version All authors acknowledge financial support from the SCARCE project, which is supported by the National Research Foundation, Singapore, and National Environment Agency, Singapore under its Closing the Waste Loop Funding Initiative (Award No. USS-IF-2018-4).

The high cost and scarcity of lithium resources have prompted researchers to seek alternatives to lithium-ion batteries. Among emerging "Beyond Lithium" batteries, rechargeable aluminum-ion batteries (AIBs) are yet another attractive electrochemical storage device due to their high specific capacity and the abundance of aluminum. Although the current electrochemical performance of nonaqueous AIBs is better than aqueous AIBs (AAIBs), AAIBs have recently gained attention due to their low cost and enhanced safety. Extensive efforts are devoted to developing AAIBs in the last few years. Yet, it is still challenging to achieve stable electrodes with good electrochemical performance and electrolytes without side reactions. This review summarizes the recent progress in the exploration of anode and cathode materials and the selection of electrolytes of AAIBs. Lastly, the main challenges and future research outlook of high-performance AAIBs are also presented. Ministry of Education (MOE) Q.Y. acknowledges the funding support from Singapore MOE AcRF Tier 1 under grant no. 2020-T1-001-031

As the most common primary tumour of the central nervous system, gliomas have a high recurrence rate after surgical resection and are resistant to chemotherapy, particularly high‑grade gliomas dominated by glioblastoma multiforme (GBM). The prognosis of GBM remains poor despite improvements in treatment modalities, posing a serious threat to human health. At present, although drugs such as temozolomide, cisplatin and bevacizumab, are effective in improving the overall survival of patients with GBM, most patients eventually develop drug resistance, leading to poor clinical prognosis. The development of multidrug resistance has therefore become a major obstacle to improving the effectiveness of chemotherapy for GBM. The ability to fully understand the underlying mechanisms of chemotherapy resistance and to develop novel therapeutic targets to overcome resistance is critical to improving the prognosis of patients with GBM. Of note, growing evidence indicates that a large number of abnormally expressed noncoding RNAs (ncRNAs) have a central role in glioma chemoresistance and may target various mechanisms to modulate chemosensitivity. In the present review, the roles and molecular mechanisms of ncRNAs in glioma drug resistance were systematically summarized, the potential of ncRNAs as drug resistance markers and novel therapeutic targets of glioma were discussed and prospects for glioma treatment were outlined. ncRNAs are a research direction for tumor drug resistance mechanisms and targeted therapies, which not only provides novel perspectives for reversing glioma drug resistance but may also promote the development of precision medicine for clinical diagnosis and treatment.

The fast depletion of lithium resources has led to active research work on other emerging electrochemical energy storage systems. Among those, many studies have focused on the development of cathode materials of zinc ion batteries for even higher energy efficiency, outstanding rate capability, remarkable power density, and longer lifetime. Vanadium-based nanomaterials show fast ion diffusion and excellent reversible capacity because of their rich valence state of vanadium, facile distortion of V–O polyhedrons, and tunable chemical composition, offering great opportunities for developing emerging energy storage technologies. This article systematically reviews vanadium-based nanomaterials in the cathode materials for zinc ion batteries, aiming to present a comprehensive discussion. Herein, we group vanadium-based cathode materials into three categories including vanadium oxides, vanadates, and vanadium phosphates. The cathode electrochemical performance, improvement strategies, structural stability, and zinc storage mechanism are reviewed in detail. Lastly, the existing bottlenecks and prospects are provided for further progressive research.

Electrocatalytic nitrogen reduction reaction (NRR) to generate ammonium is a promising renewable technology for nitrogen cycling. Engineering the composition and surface states of an electrocatalyst is critical to improve the intrinsic NRR performance. Here, a facile preparation of Ni nanoparticles (NPs) loaded on V4C3Tx MXene (denoted as Ni@MX) as a highly efficient NRR electrocatalyst is reported. Remarkably, the Ni@MX nanocomposite presents an ammonia yield rate of 21.29 μg h−1 mgcat−1 at 0.2 mA cm−2. The presented NRR activity is considerably higher than that of the recently reported MXene derivatives and is even comparable to that of the noble-metal-based electrocatalysts. Combined with various characterization methods and the density functional theory (DFT) simulation, we propose that the improved NRR activity was ascribed to a synergistic NRR route by Ni sites in the nanoparticles and the surface O vacancy of V4C3Tx MXene. Given the remarkable improvement of NRR activity on the MXene-based nanocomposites, this work demonstrates the critical role of MXene and its derivatives with surface modification as electrocatalysts.

Thermoelectric energy conversion is an all solid-state technology that relies on exceptional semiconductor materials that are generally optimized through sophisticated strategies involving the engineering of defects in their structure. In this review, we summarize the recent advances of defect engineering to improve the thermoelectric (TE) performance and mechanical properties of inorganic materials. First, we introduce the various types of defects categorized by dimensionality, i.e. point defects (vacancies, interstitials, and antisites), dislocations, planar defects (twin boundaries, stacking faults and grain boundaries), and volume defects (precipitation and voids). Next, we discuss the advanced methods for characterizing defects in TE materials. Subsequently, we elaborate on the influences of defect engineering on the electrical and thermal transport properties as well as mechanical performance of TE materials. In the end, we discuss the outlook for the future development of defect engineering to further advance the TE field. Agency for Science, Technology and Research (A*STAR) Submitted/Accepted version TE materials research at NTU is supported by Agency for Science, Technology and Research (A*STAR), Industry Alignment Fund, Pharos ‘‘Hybrid thermoelectric materials for ambient applications’’ Program (Grant No. 1527200019). TE materials research at Northwestern (TJS, YL, ZZL, and MGK) is supported by the U.S Department of Energy, Office of Science and Office of Basic Energy Sciences for funding under award number DE-SC0014520. YZ acknowledges the support from Hubei Provincial Natural Science Foundation of China (Grant No. 2020CFB217).