MXene/Ag2CrO4 Nanocomposite as Supercapacitors Electrode

MXene/Ag2CrO4 nanocomposite was synthesized effectively by means of superficial low-cost co-precipitation technique in order to inspect its capacitive storage potential for supercapacitors. MXene was etched from MAX powder and Ag2CrO4 spinel was synthesized by an easy sol-gel scheme. X-Ray diffraction (XRD) revealed an addition in inter-planar spacing from 4.7 Å to 6.2 Å while Ag2CrO4 nanoparticles diffused in form of clusters over MXene layers that had been explored by scanning electron microscopy (SEM). Energy dispersive X-Ray (EDX) demonstrated the elemental analysis. Raman spectroscopy opens the gap between bonding structure of as-synthesized nanocomposite. From photoluminence (PL) spectra the energy band gap value 3.86 eV was estimated. Electrode properties were characterized by applying electrochemical observations such as cyclic voltammetry along with electrochemical impedance spectroscopy (EIS) for understanding redox mechanism and electron transfer rate constant Kapp. Additionally, this novel work will be an assessment to analyze the capacitive behavior of electrode in different electrolytes such as in acidic of 0.1 M H2SO4 has specific capacitance Csp = 525 F/g at 10 mVs−1 and much low value in basic of 1 M KOH electrolyte. This paper reflects the novel synthesis and applications of MXene/Ag2CrO4 nanocomposite electrode fabrication in energy storage devices such as supercapacitors.


Introduction
The stipulate for well-groomed energy storage strategies is on the hit list in the current state of affairs. To overcome this worldwide issue, supercapacitors were used to pile up energy in electronic applications to store charge, depending upon electrochemical reactions enclosed by them [1]. Narrative layered two-dimensional (2D) material i.e., MXene (Ti 3 C 2 T x ) comprehensively deliberated to construct electrodes for supercapacitors owing to their high metallic conduction rate and reactive hydrophilic surface. In spite of all the assorted dilemmas including re-crushing and oxidizing of titanium which obstruct Ti 3 C 2 T x to achieve the significant capacitance, cheap carbon electrode material for instance Ti 3 C 2 T x , a type of MXene, participated in great technological research for development of supercapacitors electrodes by defeating these issues [2][3][4]. In composite form, Ti 3 C 2 T x deals with the above-mentioned problems due to its excellent specific capacity with lower resistance, significant surface area and the redox active nature of surface

Ag 2 CrO 4 Nanoparticles Synthesis
In order to synthesize Ag 2 CrO 4 nanoparticles, the wet chemical sol-gel method was applied. In this approach, 4 g of silver nitrate and 3 g of chromium nitrate solution was prepared in 50 mL of DI water accomplished by adding up of citric acid powder in 2:1 ratio. The aqueous solution undergone continuous stirring at 70 • C until the required homogeneous solution obtained. After viscous gel development, stirring had been stopped. In order to achieve main product, solution was positioned at oven adjusted at 700 • C for three hours and then further calcination at 600 • C in the furnace was performed. At the end, powder form of the sample grounded in agate motor to get homogeneous fine powder. The chemical formula of Ag 2 CrO 4 was explained by chemical Equations (1) and (2) given below [32]. Ag = Ag + + e − (1) 2Ag + + CrO 4 −2 = Ag 2 CrO 4 (2) The obtained powder of Ag 2 CrO 4 nanoparticles was used to synthesize nanocomposite of MXene/Ag 2 CrO 4 .

Synthesis of MXene (Ti 3 C 2 T x )
MXene was synthesized using the conventional method. First, 10 g of formerly prepared MAX powder were taken in a teflon bottle with 200 mL (39%) intense HF to synthesize Ti 3 C 2 T x (MXene). Hydrofluoric acid (HF) and MAX powder was homogeneously blended by constant stirring for 36 h, at room temperature. Later, the hot plate was removed, and the solution was placed to cool down for 12 h. Moreover, the mixture was again stirred for 12 h. At the end, the resultant solution was rinsed several times by using deionized (DI) water followed by vacuum filtration. By drying the solution at 60 • C for 12 h, the etched MXene obtained is used for assembling of nanocomposite [33].

Synthesis of MXene/Ag 2 CrO 4 Nanocomposite
The easily available wet chemical method, namely the co-precipitation method, was used to synthesize nanocomposite of MXene/Ag 2 CrO 4 in which the solution of MXene prepared in 200 mL DI water by taking 200 mg of Ti 3 C 2 T x (MXene) under sonication for 10 min. At the same time already prepared Ag 2 CrO 4 nanoparticles were assorted in 100 mL acetic acid and 100 mL ethylene glycol in a stoichiometric proportion of 1:1 with 0.01 M (morality). Sonication of MXene solution was performed at 3500 rpm for 120 min at 60 • C to obtain homogeneous sample. Then, both solutions were thoroughly mixed by continuous stirring at 80 • C for 1 hr. After that the settled solution was washed many times with DI water unless neutral solution was obtained. An oven was used at 70 • C for 24 h until it is completely dried. Obtained nano-powder became homogenous using an agate motor.

X-ray Diffraction (XRD) Analysis
The structure of the resultant sample was analyzed by X-Ray diffraction (XRD) technique with monochromatic wavelength λ (1.5 Å) in which corresponding (hkl) values were assigned approximately to all peaks. In Figure 1, the XRD pattern of bare Ag 2 CrO 4 nanoparticles representing an orthorhombic structure with the JCPDS no. 026 [34]. The prominently solid and high-pitched peaks proved pure and well-crystalline Ag 2 CrO 4 collected by the stated process [35]. The characteristic peaks of MAX at 9.5 • and 19.2 • angles with (002) and (004) planes transferred towards left due to etched aluminum (Al) peaks resulting an increase in the spacing between sheets of resulting etched MAX powder so-called MXene (Ti 3 C 2 T x ) [36]. In MXene/Ag 2 CrO 4 nanocomposite all the peaks shifted towards lower angles with low intensity, certified an increase in inter-planar spacing from 4.7 Å to 6.2 Å of MXene/Ag 2 CrO 4 nanocomposite which step up the conductivity [37]. From XRD data [38] the average crystallite size of MXene/Ag2CrO4 nanocomposite was calculated by Debye-Scherrer Equation (3) given below.
In general, crystalline size D in nm, X-ray wavelength λ is 0.15 nm, θ is the Bragg's angle in radian, β full width half maximum of diffracted beams. The average crystallite size of MXene/Ag2CrO4 nanocomposite is 14 nm analogous to other MXene composite [39,40]. The presence of characteristic peaks of Ag2CrO4 and MXene in the nanocomposite sample is an indication of the successful development of MXene/Ag2CrO4 nanocomposite.

The Scanned Electronic Microscopic Analysis
The scanned electron microscopic (SEM) analysis of the synthesized sample explained the surface morphology of MXene/Ag2CrO4 nanocomposite. The purpose was to see how MXene and Ag2CrO4 nanoparticles coordinated with each other, including the even and continuous layered form of MXene with sharp edges gained after selective etching of aluminum (Al) layer by HF etching method as shown in Figure 2a. The SEM images of the Ti3C2Tx/Ag2CrO4 nanocomposite sample are shown in Figure 2b in which nanoparticles of Ag2CrO4 adorned the surface of Ti3C2Tx in random pattern forming coagulated structure and explored huge clusters of the nanoparticles. Hence, only some grains scattered on layers of MXene. The number of nanoparticles nucleated on the surface of MXene engraved pores caused more storage capacity [41][42][43][44]. The average diameter of Ag2CrO4 nanoparticles is 75 nm reported in [32], here 3.67 nm is the grain size of MXene/Ag2CrO4 nanocomposite calculated by using image J. software. Here, clearly, it can be seen Ag2CrO4 nanoparticles in the MXene/Ag2CrO4 nanocomposite were reduced suggestively and closely occupied the MXene sheets. Furthermore, grain size distribution histogram shown in Figure 3 summarizing discrete or continuous data on an interval scale, respectively. From XRD data [38] the average crystallite size of MXene/Ag 2 CrO 4 nanocomposite was calculated by Debye-Scherrer Equation (3) given below.
In general, crystalline size D in nm, X-ray wavelength λ is 0.15 nm, θ is the Bragg's angle in radian, β full width half maximum of diffracted beams. The average crystallite size of MXene/Ag 2 CrO 4 nanocomposite is 14 nm analogous to other MXene composite [39,40]. The presence of characteristic peaks of Ag 2 CrO 4 and MXene in the nanocomposite sample is an indication of the successful development of MXene/Ag 2 CrO 4 nanocomposite.

The Scanned Electronic Microscopic Analysis
The scanned electron microscopic (SEM) analysis of the synthesized sample explained the surface morphology of MXene/Ag 2 CrO 4 nanocomposite. The purpose was to see how MXene and Ag 2 CrO 4 nanoparticles coordinated with each other, including the even and continuous layered form of MXene with sharp edges gained after selective etching of aluminum (Al) layer by HF etching method as shown in Figure 2a. The SEM images of the Ti 3 C 2 T x /Ag 2 CrO 4 nanocomposite sample are shown in Figure 2b in which nanoparticles of Ag 2 CrO 4 adorned the surface of Ti 3 C 2 T x in random pattern forming coagulated structure and explored huge clusters of the nanoparticles. Hence, only some grains scattered on layers of MXene. The number of nanoparticles nucleated on the surface of MXene engraved pores caused more storage capacity [41][42][43][44]. The average diameter of Ag 2 CrO 4 nanoparticles is 75 nm reported in [32], here 3.67 nm is the grain size of MXene/Ag 2 CrO 4 nanocomposite calculated by using image J. software. Here, clearly, it can be seen Ag 2 CrO 4 nanoparticles in the MXene/Ag 2 CrO 4 nanocomposite were reduced suggestively and closely occupied the MXene sheets. Furthermore, grain size distribution histogram shown in Figure 3 summarizing discrete or continuous data on an interval scale, respectively. Materials 2021, 14, x 5 of 14

Energy Dispersive X-ray Spectroscopy (EDX)
The spectroscopy of energy dispersion analysis of Ag2CrO4 nanoparticles and MXene/Ag2CrO4 powder are exhibited in Figure 4a,b, respectively, where not only the Ag, Cr and Ti signals seemed but also the O signal appeared due to oxidation of MXene concerned with some functional groups. This provided the proof of perfect synthesis of current nanocomposite [45]. The elements presented in spectra as per EDX analysis according to weight percentage is confirmation of the ideal synthesis of the required MXene/Ag2CrO4 nanocomposite as shown in Table 1.

Energy Dispersive X-ray Spectroscopy (EDX)
The spectroscopy of energy dispersion analysis of Ag2CrO4 nanoparticles and MXene/Ag2CrO4 powder are exhibited in Figure 4a,b, respectively, where not only the Ag, Cr and Ti signals seemed but also the O signal appeared due to oxidation of MXene concerned with some functional groups. This provided the proof of perfect synthesis of current nanocomposite [45]. The elements presented in spectra as per EDX analysis according to weight percentage is confirmation of the ideal synthesis of the required MXene/Ag2CrO4 nanocomposite as shown in Table 1.

Energy Dispersive X-ray Spectroscopy (EDX)
The spectroscopy of energy dispersion analysis of Ag 2 CrO 4 nanoparticles and MXene/ Ag 2 CrO 4 powder are exhibited in Figure 4a,b, respectively, where not only the Ag, Cr and Ti signals seemed but also the O signal appeared due to oxidation of MXene concerned with some functional groups. This provided the proof of perfect synthesis of current nanocomposite [45]. The elements presented in spectra as per EDX analysis according to weight percentage is confirmation of the ideal synthesis of the required MXene/Ag 2 CrO 4 nanocomposite as shown in Table 1. The spectroscopy of energy dispersion analysis of Ag2CrO4 nanoparticles MXene/Ag2CrO4 powder are exhibited in Figure 4a,b, respectively, where not only th Cr and Ti signals seemed but also the O signal appeared due to oxidation of MXene cerned with some functional groups. This provided the proof of perfect synthesis o rent nanocomposite [45]. The elements presented in spectra as per EDX analysis accor to weight percentage is confirmation of the ideal synthesis of the req MXene/Ag2CrO4 nanocomposite as shown in Table 1.

Raman Spectroscopy
Here, Raman spectroscopy has been employed to illustrate extremely respons composition of the material structure having incredibility and a more mechanically i portant spectroscopic technique to probe the dynamic vibrational phonons Ti3C2Tx/Ag2CrO4 nanocomposite [46]. The Raman spectra of MXene (Ti3C2Tx) was det mined at 155 cm −1 showing a vibrational band of anatase phase of TiO2 [47]. Phono (lattice vibrations) at the interface of MXene and traces of transition metal oxides w handled by Raman spectroscopy. Two main causes of lattice viberations in MXene bas materials one, surface functional groups involved stimulating pseudocapacitance and other, exchanging of ion gave rise to storing charge leading to a high capacitance MXene/Ag2CrO4 nanocomposite in acidic solution [48,49].
Raman spectroscopy of MXene/Ag2CrO4 nanocomposite noted at wavelength 532 and power 150 mW showing a characteristic peak at definite position 0.86 cm −1 wit remarkable intensity confirmed the occurrence of the prepared nanocomposite mos due to the existence of functional groups involed [50] as shown in Figure 5.

Raman Spectroscopy
Here, Raman spectroscopy has been employed to illustrate extremely responsive composition of the material structure having incredibility and a more mechanically important spectroscopic technique to probe the dynamic vibrational phonons of Ti 3 C 2 T x /Ag 2 CrO 4 nanocomposite [46]. The Raman spectra of MXene (Ti 3 C 2 T x ) was determined at 155 cm −1 showing a vibrational band of anatase phase of TiO 2 [47]. Phonons (lattice vibrations) at the interface of MXene and traces of transition metal oxides were handled by Raman spectroscopy. Two main causes of lattice viberations in MXene based materials one, surface functional groups involved stimulating pseudocapacitance and the other, exchanging of ion gave rise to storing charge leading to a high capacitance of MXene/Ag 2 CrO 4 nanocomposite in acidic solution [48,49].
Raman spectroscopy of MXene/Ag 2 CrO 4 nanocomposite noted at wavelength 532 nm and power 150 mW showing a characteristic peak at definite position 0.86 cm −1 with a remarkable intensity confirmed the occurrence of the prepared nanocomposite mostly due to the existence of functional groups involed [50] as shown in Figure 5.
Raman spectroscopy of MXene/Ag2CrO4 nanocomposite noted at wavelength 5 and power 150 mW showing a characteristic peak at definite position 0.86 cm −1 w remarkable intensity confirmed the occurrence of the prepared nanocomposite m due to the existence of functional groups involed [50] as shown in Figure 5.

Photoluminescence (PL) Spectroscopy
The optical spectra of MXene/Ag 2 CrO 4 nanocomposites were explained by using 325 nm wavelength of He-Cd laser at room temperature with 40 MW power. At 300 nm wavelength, the optical band gap 3.86 eV calculated in the visible region is indication of the allocation of nanoparticles clearly seen in Figure 6. The photoluminescence (PL) spectra of Ti 3 C 2 T x /Ag 2 CrO 4 nanocomposite explored high intensity emission peak at 321 nm which was mainly due to electron-hole pair recombination of sp 2 hybridized carbon atoms [51,52]. Due to defects in the structure of Ag 2 CrO 4 the photoluminescence emission properties were possible at room temperature [34]. The recommended speed of charges transported by light irradiation effect on the Ti 3 C 2 T x /Ag 2 CrO 4 nanocomposite in which valence band (VB) negative charges near to the ground skip to the conducting band (CB) due to complex photoluminescence scheme. When light was projected, positive and negative charges in aqueous medium coupled to produce radicals on the exterior of the Ti 3 C 2 T x /Ag 2 CrO 4 nanocomposite [53].

Photoluminescence (PL) Spectroscopy
The optical spectra of MXene/Ag2CrO4 nanocomposites were explained by using 325 nm wavelength of He-Cd laser at room temperature with 40 MW power. At 300 nm wavelength, the optical band gap 3.86 eV calculated in the visible region is indication of the allocation of nanoparticles clearly seen in Figure 6. The photoluminescence (PL) spectra of Ti3C2Tx/Ag2CrO4 nanocomposite explored high intensity emission peak at 321 nm which was mainly due to electron-hole pair recombination of sp 2 hybridized carbon atoms [51,52]. Due to defects in the structure of Ag2CrO4 the photoluminescence emission properties were possible at room temperature [34]. The recommended speed of charges transported by light irradiation effect on the Ti3C2Tx/Ag2CrO4 nanocomposite in which valence band (VB) negative charges near to the ground skip to the conducting band (CB) due to complex photoluminescence scheme. When light was projected, positive and negative charges in aqueous medium coupled to produce radicals on the exterior of the Ti3C2Tx/Ag2CrO4 nanocomposite [53].

Electrochemical Analysis
In order to perform the electrochemical analysis at Gamry potentiostat interface 1000, a three electrode assembly was taken where platinum wire, glassy carbon electrode (GCE) and Ag/AgCl were used as counter, working and reference electrodes, respectively [54,55]. The working electrode was rinsed many times using an alumina slurry and ethanol prior to production of synthesis material. To fabricate GCE, 0.25 g powder of electrode material was used with 2 µ L of 5% nafion solution on glassy carbon electrode [56]. The functional electrode underwent drying in an oven at 50 °C for 20 min.

Electrochemical Analysis
In order to perform the electrochemical analysis at Gamry potentiostat interface 1000, a three electrode assembly was taken where platinum wire, glassy carbon electrode (GCE) and Ag/AgCl were used as counter, working and reference electrodes, respectively [54,55]. The working electrode was rinsed many times using an alumina slurry and ethanol prior to production of synthesis material. To fabricate GCE, 0.25 g powder of electrode material was used with 2 µL of 5% nafion solution on glassy carbon electrode [56]. The functional electrode underwent drying in an oven at 50 • C for 20 min.

Electrochemical Impedance Spectroscopy (EIS)
The electrochemical impedance spectroscopy (EIS) was adopted to study the dependence of capacitance of supercapacitors on the applied power in which an alternating current voltage of 0.5 V and zero direct current voltage was utilized and current passes through electrode (metal or semiconductors) at working position [57]. The electron transferred properties of Ti 3 C 2 T x /Ag 2 CrO 4 were studied by using EIS. The Nyquist plots drawn for Ti 3 C 2 T x /Ag 2 CrO 4 in 0.1 M H 2 SO 4 and 1 M KOH were displayed in Figure 7, also concerned EIS parameters were given in Table 2. The differences in electrochemical behavior of the as-synthesized electrocatalysts depend upon the relative feasibility of electron transfer. Low charge transfer resistance R p due to elevated conduction, facilitated more electrons in the electrode surface and the current electrocatalysts showed a low R p value [58] with high conductivity in acidic media, hence a higher specific capacitance C sp value was achieved. The nature of the electrodes exhibited no influence on the solution resistance (Ru) and Warburg resistance (Rw) because these are features of the electrolyte and diffusion of electroactive specie that are common in all observations. However, (R p ) and phase constant element (CPE) are influenced by modification of electrodes, as they are associated with conductive properties of the active material. Here α represents surface roughness factor and its value varies from 0 to 1. Herein, currently modified electrode system has α value 0.85 and 0.89 revealing that catalysts depicted enough surface roughness. The electron-transfer rate constant K app (cm s −1 ) for planned catalysts was deliberated using the following Equation (4) [59]. Moreover, the fitted EIS model i.e., CPE with the diffusion model has been represented in the inset of Nyquist plots in Figure 7. transfer. Low charge transfer resistance Rp due to elevated conduction, facilitated more electrons in the electrode surface and the current electrocatalysts showed a low Rp value [58] with high conductivity in acidic media, hence a higher specific capacitance Csp value was achieved. The nature of the electrodes exhibited no influence on the solution resistance (Ru) and Warburg resistance (Rw) because these are features of the electrolyte and diffusion of electroactive specie that are common in all observations. However, (Rp) and phase constant element (CPE) are influenced by modification of electrodes, as they are associated with conductive properties of the active material. Here α represents surface roughness factor and its value varies from 0 to 1. Herein, currently modified electrode system has α value 0.85 and 0.89 revealing that catalysts depicted enough surface roughness. The electron-transfer rate constant Kapp (cm s -1 ) for planned catalysts was deliberated using the following Equation (4) [59]. Moreover, the fitted EIS model i.e., CPE with the diffusion model has been represented in the inset of Nyquist plots in Figure 7.
Here, F served as the Faraday constant, C corresponds to amount of analyte and R is the universal constant in SI units.    Here, F served as the Faraday constant, C corresponds to amount of analyte and R is the universal constant in SI units.
The poorer K app in 1 M KOH aqueous electrolyte solution corresponds to relatively lower electron conductivity as compared to acidic electrolyte.

Electrochemical Active Surface Area (ECSA) Analysis
The electrochemically active surface area (ECSA) is an important performance indicator of a catalyst in any electrochemical reaction and for this reason cyclic voltammograms of all prepared electrocatalysts were recorded in a standard redox solution of 5 mM potassium ferrocyanide (K 4 [Fe (CN) 6 ]) and 3M potassium chloride (KCl) at 100 mVs −1 for ECSA inference [60]. Peak current (i p ) increment in the CV profile correspond to a reversible one-electron transfer process using the synthesized nanocomposite as modified electrodes in K 4 [Fe (CN) 6 ] electrolyte. This observation of a reversible CV profile was used to point out the oxidation and reduction methods by an overall redox process as shown in Figure 8. The ECSA of electrode was calculated by applying the Randles-Sevcik Equation (5)  The electrochemically active surface area (ECSA) is an important performance indicator of a catalyst in any electrochemical reaction and for this reason cyclic voltammograms of all prepared electrocatalysts were recorded in a standard redox solution of 5 mM potassium ferrocyanide (K4[Fe (CN)6]) and 3M potassium chloride (KCl) at 100 mVs −1 for ECSA inference [60]. Peak current (ip) increment in the CV profile correspond to a reversible one-electron transfer process using the synthesized nanocomposite as modified electrodes in K4[Fe (CN)6] electrolyte. This observation of a reversible CV profile was used to point out the oxidation and reduction methods by an overall redox process as shown in Figure 8. The ECSA of electrode was calculated by applying the Randles-Sevcik Equation (5) [61]. ip = 2.69 × 10 5 ·n 3/2 ·A·D 1/2 ·υ 1/2 ·C (5) Here ip is the peak current, n is the count of transferred electrons, A is the electrochemical active surface area (cm 2 ), D corresponds to the diffusion co-efficient, ʋ represents the scan rate (Vs −1 ), C is analytic amount [62]. With a peak current value of 132 μA, the ECSA of observed electrode is 0.04 cm 2 that referred to efficient capacitive performance of the electrode material.

Electrochemical Investigations
The electrochemical performances of Ti3C2Tx/Ag2CrO4 nanocomposite were evaluated by cyclic voltammetry (CV) by varying the electrode potential between a working electrode and reference electrode in order to measure current flows between working and counter electrodes. By using the modified working electrodes in both acidic and basic electrolytes to analyze the electrode potential in both media, the acid electrolyte has the advantage in providing protons for as synthesized nanocomposite in cyclic voltammetry [63]. The capacitive behavior of the nanocomposite was observed in forward and reverse directions relative to the anodic peaks (oxidation) and cathodic peaks (reduction) which is the verification of surface redox reactions. The specific capacitance of working electrode Ti3C2Tx/Ag2CrO4 nanocomposite was calculated using Equation (6).
where Csp is specific capacitance in F/g, m is used for mass of electrode i.e., 0.25 mg, k Here i p is the peak current, n is the count of transferred electrons, A is the electrochemical active surface area (cm 2 ), D corresponds to the diffusion co-efficient, υ represents the scan rate (Vs −1 ), C is analytic amount [62]. With a peak current value of 132 µA, the ECSA of observed electrode is 0.04 cm 2 that referred to efficient capacitive performance of the electrode material.

Electrochemical Investigations
The electrochemical performances of Ti 3 C 2 T x /Ag 2 CrO 4 nanocomposite were evaluated by cyclic voltammetry (CV) by varying the electrode potential between a working electrode and reference electrode in order to measure current flows between working and counter electrodes. By using the modified working electrodes in both acidic and basic electrolytes to analyze the electrode potential in both media, the acid electrolyte has the advantage in providing protons for as synthesized nanocomposite in cyclic voltammetry [63]. The capacitive behavior of the nanocomposite was observed in forward and reverse directions relative to the anodic peaks (oxidation) and cathodic peaks (reduction) which is the verification of surface redox reactions. The specific capacitance of working electrode Ti 3 C 2 T x /Ag 2 CrO 4 nanocomposite was calculated using Equation (6).
where C sp is specific capacitance in F/g, m is used for mass of electrode i.e., 0.25 mg, k represents the scan rate and A denotes integrated area under CV curve and V corresponds to potential window −0.2 V to 0.6 V. The estimated electrochemical capacitance parameters are summarized in Table 3. Cyclic voltammetry demonstrated capacitive performance of Ti 3 C 2 T x /Ag 2 CrO 4 electrode at different scan rate as shown in Figure 9. The highest C sp = 525 F/g was attained at 10 mVs −1 in 0.1M H 2 SO 4 . Clearly, it can be seen from Table 3 that the specific capacitance and scan rate are inversely related. With an increase in scan rates, capacitance will be low owing to low charge storage ability of electrode material [64]. Enhanced specific capacitance with small area utilization by ions of electrolyte at a low scan rate is important to note down [65]. Synthesized Ti 3 C 2 T x /Ag 2 CrO 4 nanocomposite exhibits comparatively improved capacitance output even at lower concentration of acidic electrolyte. Comparison of Ti 3 C 2 T x /Ag 2 CrO 4 nanocomposite with other nanocomposites shown in Table 4. to potential window −0.2 V to 0.6 V. The estimated electrochemical capacitance parameters are summarized in Table 3. Cyclic voltammetry demonstrated capacitive performance of Ti3C2Tx/Ag2CrO4 electrode at different scan rate as shown in Figure 9. The highest Csp = 525 F/g was attained at 10 mVs −1 in 0.1M H2SO4. Clearly, it can be seen from Table 3 that the specific capacitance and scan rate are inversely related. With an increase in scan rates, capacitance will be low owing to low charge storage ability of electrode material [64]. Enhanced specific capacitance with small area utilization by ions of electrolyte at a low scan rate is important to note down [65]. Synthesized Ti3C2Tx/Ag2CrO4 nanocomposite exhibits comparatively improved capacitance output even at lower concentration of acidic electrolyte. Comparison of Ti3C2Tx/Ag2CrO4 nanocomposite with other nanocomposites shown in Table 4.

Conclusions
MXene (Ti 3 C 2 T x ) based silver-chromite nanocomposite special treatment particularly in the field of energy storage application is reported. XRD showed enhanced inter-planar spacing from 4.7 Å to 6.2 Å. SEM images revealed silver chromite nanoparticles attachment to MXene sheets whereas EDX confirmed the presence of silver chromite within the nanocomposite. Raman spectroscopy and photoluminescence revealed functional groups' attachment and a band gap value of about 3.86 eV. MXene/Ag 2 CrO 4 nanocompositebased electrode in 0.1M H 2 SO 4 electrolyte have 525 F/g capacitance at a scan rate of 10 mVs −1 instead of its lower value of 75 F/g at 20 mVs −1 in case of 1M KOH. Thus, pseudocapacitive behavior in the acidic media gives maximum charge storage in the case of the Ti 3 C 2 T x /Ag 2 CrO 4 electrode, as compared to basic media. MXene type materials in nanocomposite form with significant capacitance in the near panorama give strategy to suggest more search. Here specific capacity of Ti 3 C 2 T x /Ag 2 CrO 4 electrode faraway from ideal value, for this reason there is need for progress in the instruction about surface functional groups.