Decreased Surface Photovoltage of ZnO Photoanode Films via Optimal Annealing Temperature for Enhanced Photoelectrochemical Performance

<div>(a) UV-vis absorption spectra and (b) the corresponding <svg height="13.8595pt" id="M16" style="vertical-align:-2.2681pt" version="1.1" viewbox="-0.0498162 -11.5914 34.745 13.8595" width="34.745pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M300 -147C201 -63 143 98 143 270S200 602 300 686L282 710C136 610 70 450 70 271V270C70 89 136 -72 282 -170L300 -147Z"></path></g><g transform="matrix(.013,0,0,-0.013,4.498,0)"><path d="M545 106L524 126C493 85 467 65 455 65C438 65 427 113 405 238C448 295 498 362 543 439L533 448L478 435C453 386 423 331 398 295H395C370 404 347 448 282 448C169 448 23 309 23 153C23 54 65 -12 128 -12C203 -12 283 70 339 155H341C360 29 380 -12 411 -12C444 -12 491 11 545 106ZM333 204C265 95 210 54 169 54C137 54 113 96 113 171C113 302 191 405 252 405C301 405 318 306 333 204Z"></path></g><g transform="matrix(.013,0,0,-0.013,12.144,0)"><path d="M499 88L487 113C459 86 422 65 413 65C403 65 403 74 409 98L461 318C487 426 460 448 431 448C408 448 383 441 352 424C305 398 223 344 157 257H155L243 674C249 702 249 712 240 712C227 712 170 680 87 673L82 648H117C155 648 162 644 150 590L23 -4L30 -12C55 -4 81 3 105 8C113 53 131 150 143 187C199 281 323 387 372 387C390 387 393 369 380 311L328 86C313 19 319 -12 347 -12C379 -12 442 24 499 88Z"></path></g><g transform="matrix(.013,0,0,-0.013,18.852,0)"><path d="M457 332C457 400 429 448 397 448C384 448 371 441 365 435L366 428C376 413 388 372 388 315C388 152 306 45 220 45C166 45 134 85 158 180L197 332C204 361 207 385 207 402C207 434 196 448 174 448C125 448 66 406 23 342L43 319C84 368 110 383 121 383C130 383 129 374 122 343L76 156C71 137 69 120 69 105C69 25 125 -12 181 -12C314 -12 457 166 457 332Z"></path></g><g transform="matrix(.013,0,0,-0.013,25.094,0)"><path d="M275 270C275 450 212 609 64 710L45 686C145 604 203 442 203 270S147 -63 45 -147L64 -170C213 -68 275 89 275 270Z"></path></g><g transform="matrix(.0091,0,0,-0.0091,29.592,-5.741)"><path d="M414 144C384 79 371 75 317 75H135L276 221C367 316 408 376 408 465C408 570 327 635 237 635C179 635 131 609 100 575L42 494L67 471C94 510 138 565 205 565C277 565 321 517 321 435C321 348 258 270 195 195C146 137 88 81 33 26V0H411C423 44 433 88 446 135L414 144Z"></path></g></svg> vs. <svg height="9.49473pt" id="M17" style="vertical-align:-0.2063999pt" version="1.1" viewbox="-0.0498162 -9.28833 13.0962 9.49473" width="13.0962pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M499 88L487 113C459 86 422 65 413 65C403 65 403 74 409 98L461 318C487 426 460 448 431 448C408 448 383 441 352 424C305 398 223 344 157 257H155L243 674C249 702 249 712 240 712C227 712 170 680 87 673L82 648H117C155 648 162 644 150 590L23 -4L30 -12C55 -4 81 3 105 8C113 53 131 150 143 187C199 281 323 387 372 387C390 387 393 369 380 311L328 86C313 19 319 -12 347 -12C379 -12 442 24 499 88Z"></path></g><g transform="matrix(.013,0,0,-0.013,6.708,0)"><path d="M457 332C457 400 429 448 397 448C384 448 371 441 365 435L366 428C376 413 388 372 388 315C388 152 306 45 220 45C166 45 134 85 158 180L197 332C204 361 207 385 207 402C207 434 196 448 174 448C125 448 66 406 23 342L43 319C84 368 110 383 121 383C130 383 129 374 122 343L76 156C71 137 69 120 69 105C69 25 125 -12 181 -12C314 -12 457 166 457 332Z"></path></g></svg> curves of unannealed ZnO, ZnO-350, ZnO-450, and ZnO-550. Photoluminescence (PL) spectra of unannealed ZnO, ZnO-350, ZnO-450, and ZnO-550: (c) 300~720 nm and (d) 370~450 nm.</div>

Journal of Nanomaterials

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Figure 3

Figure 3: Decreased Surface Photovoltage of ZnO Photoanode Films via Optimal Annealing Temperature for Enhanced Photoelectrochemical Performance 